Problem: Given the question: Because of human activities, there is more carbon dioxide in the atmosphere today than in the past hundreds of thousands of years. Burning fossil fuels and has released great quantities of carbon dioxide into the atmosphere. Cutting forests and clearing land has also increased carbon dioxide into the atmosphere because these activities reduce the number of autotrophic organisms that use up carbon dioxide in photosynthesis. In addition, clearing often involves burning, which releases carbon dioxide that was previously stored in autotrophs.  When comparing village A from ten thousand years ago to village B from today, we reached the conclusion that today's villagers release much more carbon into the atmosphere by their activities.  Which village cleared less land?
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The answer is:
village A


Problem: Given the question: The epidermis also contains melanocytes , which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D . Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency.  An anthropologist gathered observations for two native tribes from southern Africa.  He noticed that both tribes spend the majority of the day outside, and therefore they are both exposed to fairly high amounts of UV light. He also quickly realized that one key difference between the tribes was that members of tribe A had dark skin, while members of tribe B had light skin.  Members of which tribe will block less UV light from penetrating their skin?
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The answer is:
tribe B


Problem: Given the question: Recall that air pollution is due to chemical substances and particles released into the air mainly by human actions. When most people think of air pollution, they think of the pollution outdoors. But it is just as easy to have indoor air pollution. Your home or school classroom probably doesn't get much fresh air. Sealing up your home reduces heating and cooling costs. But this also causes air pollution to stay trapped indoors. And people today usually spend a majority of their time indoors. So exposure to indoor air pollution can become a significant health risk.  Two neighboring cities had very different health related problems. Twin city had increased air pollution, their people experiencing all kinds of respiratory diseases, while Pine city had problems with age related diseases.  Which city had fewer people exposed to chemical particles released into the air by human actions?
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The answer is:

Pine