[Q]: I read this background article the other day: Around 5.4 billion years from now, the core of the Sun will become hot enough to trigger hydrogen fusion in its surrounding shell. This will cause the outer layers of the star to expand greatly, and the star will enter a phase of its life in which it is called a red giant. Within 7.5 billion years, the Sun will have expanded to a radius of 1.2 AU—256 times its current size. At the tip of the red giant branch, as a result of the vastly increased surface area, the Sun's surface will be much cooler (about 2600 K) than now and its luminosity much higher—up to 2,700 current solar luminosities. For part of its red giant life, the Sun will have a strong stellar wind that will carry away around 33% of its mass. During these times, it is possible that Saturn's moon Titan could achieve surface temperatures necessary to support life.As the Sun expands, it will swallow the planets Mercury and Venus. Earth's fate is less clear; although the Sun will envelop Earth's current orbit, the star's loss of mass (and thus weaker gravity) will cause the planets' orbits to move farther out. If it were only for this, Venus and Earth would probably escape incineration, but a 2008 study suggests that Earth will likely be swallowed up as a result of tidal interactions with the Sun's weakly bound outer envelope.Gradually, the hydrogen burning in the shell around the solar core will increase the mass of the core until it reaches about 45% of the present solar mass. At this point the density and temperature will become so high that the fusion of helium into carbon will begin, leading to a helium flash; the Sun will shrink from around 250 to 11 times its present (main-sequence) radius. Consequently, its luminosity will decrease from around 3,000 to 54 times its current level, and its surface temperature will increase to about 4770 K. The Sun will become a horizontal giant, burning helium in its core in a stable fashion much like it burns hydrogen today. The helium-fusing stage will last only 100 million years. Eventually, it will have to...  I am facing a new situation today: Keith was playing a simulation game. In the game he could travel around the Sun in the future. He started the game in  present time, which was denoted as time A. Then he traveled 5.4 billion years into the future, which was denoted as time B. Finally, he reached 7.5 billion years into the future, which was denoted as time C. He was amazed to find how the Sun would change over time.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: When would the size of the Sun be smaller, time A or time C?
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[A]: time A


[Q]: I read this background article the other day: Rainfall in an area is important because it influences the rate of weathering. More rain means that more rainwater passes through the soil. The rainwater reacts chemically with the particles. The top layers of soil are in contact with the freshest water, so reactions are greatest there. High rainfall increases the amount of rock that experiences chemical reactions. High rainfall may also carry material away. This means that new surfaces are exposed. This increases the rate of weathering.  I am facing a new situation today: Rob is an environmental scientist. He is looking at two samples of soil, sample A and sample B. Sample A is from Amazon Rain-forest, where they get one of the highest rainfall in the world. Sample B is from the Atacama Desert, where they get one of the lowest rainfall in the world. He needs to determine the properties of these samples.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Would sample A rocks have more or less chemical reactions?
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[A]: more


[Q]: I read this background article the other day: Any unused energy in food—whether it comes from carbohydrates, proteins, or lipids—is stored in the body as fat. An extra 3,500 Calories of energy results in the storage of almost half a kilogram (1 pound) of stored body fat. People who consistently consume more food energy then they need may become obese. Obesity occurs when the body mass index is 30.0 kg/m 2 or greater. Body mass index (BMI) is an estimate of the fat content of the body. It is calculated by dividing a person’s weight (in kilograms) by the square of the person’s height (in meters). Obesity increases the risk of health problems such as type 2 diabetes and hypertension.  I am facing a new situation today: Roger and Samantha are brother and sister. Both of them perform roughly the same amount of physical activity on a day-to-day basis. Roger, however, eats a lot more food relative to the amount he needs given his activity levels. Samantha, on the other hand, eats the appropriate amount of food given her level of activity.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Who is less likely to gain fat?
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[A]: Samantha


[Q]: I read this background article the other day: The body's second line of defense against pathogens includes the inflammatory response. If bacteria enter the skin through a scrape, the area may become red, warm, and painful. These are signs of inflammation. Inflammation is one way the body reacts to infections or injuries. Inflammation is caused by chemicals that are released when skin or other tissues are damaged. The chemicals cause nearby blood vessels to dilate, or expand. This increases blood flow to the damaged area, which makes the area red and slightly warm. The chemicals also attract white blood cells called neutrophils to the wound and cause them to leak out of blood vessels into the damaged tissue.  I am facing a new situation today: Ryan is carrying groceries from his car back to his apartment when he trips and falls landing on his knees. Embarrassed, he gets back up, picks up his groceries and carries them into his apartment with his head down. After putting his groceries away, he notices that although both of his knees are scraped, only his left knee is warm to the touch. His right knee feels cool when he puts his hand on it.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Is more blood flowing to the right or left knee?
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[A]:
left knee