In this task, you're given an article, a question which often contains a blank and four options (associated with "A", "B", "C", "D"). Your task is to find the correct answer (from the given options) for the question from the given article and return one of the options from "A", "B", "C", and "D". Do not generate anything else apart from one of the following characters: "A", "B", "C", "D". There is only one correct answer for each question.
One example: Article: Homework can put you in a bad mood , and that might actually be a good thing. Researchers from the University of Plymouth in England doubted whether mood might affect the way kids learn. To find out the answer, they did two experiments with children. The first experiment tested 30 kids. Someshapes were hidden inside a different, larger picture. The kids had to find the small shapes while sitting in a room with either cheerful or sad music playing in the background. To test their mood, the scientists asked the kids to point to one of five faces, from happy to sad. Children who listened to cheerful music tended to point to the smiley faces while the others pointed to the unhappy ones. The researchers found that sad kids took at least a second less to find the small shapes. They also found an average of three or four more shapes. In the second experiment, 61 children watched one of two scenes from a film. One scene was happy, and the other was sad. Just like in the first experiment, kids who saw the sad scene acted better compared to the others. The researchers guessed that feeling down makes people more likely to focus on a problem or difficult situation. Not all scientists agree with them, however. Other studies argued that maybe, that cheerful music in the first experiment distracted kids from finding shapes. While scientists work on finding out the answers, it still might be wise to choose when to do your tasks according to your mood. After eating a delicious ice cream, for example, write an essay. 
 Question: Researchers did experiments on kids in order to find out _ . 
 Options: (A) how they really feel when they are learning (B) whether mood affects their learning ability (C) what methods are easy for kids to learn (D) the relationship between sadness and happiness
Solution is here: B
Explanation: It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment. So, B is the correct answer.

Now, solve this: Article: Most of the time, the ground feels solid beneath our feet. That's comforting. But it's also misleading because there's actually a lot going on underground. Masses of land (called plates) slip, slide, and bump against each other, slowly changing the shape of continents and oceans over millions and billions of years. Scientists know that Earth formed about 4. 5 billion years ago.  They also know that our planet was hot at first. As it cooled, its outermost layer, called the crust  , eventually formed moving plates. Exactly when this shift happened, however, is an open question. Now, an international group of researchers has an answer. They've found new evidence suggesting that Earth's crust started shifting at least 3.8 billion years ago. The new estimate is l. 3 billion years earlier than previous ones. Not long before 3. 8 billion years ago,  lots of small planets were hitting Earth, keeping its crust in a hot, melting state. After the hard crust formed, much of it sank at various times into the planet's hot insides. There, it melted before returning to the surface. In some places, however, the crust never sank. One of the oldest such places is in Greenland, in an area called the Isua supracrustal   belt. The rocky crust there is between 3. 7 and 3. 8 billion years old. The belt was once part of the seafloor, but now it is exposed to air. The researchers recently took a close look at the Isua supracrustal belt. They noticed long, parallel cracks in the rock that have been filled in with a type of volcanic rock. To explain this structure, the scientists propose that tension in the crust caused the seafloor to crack open long ago. Hot, liquid rock oozed from deep inside Earth to fill the cracks. Finally, the whole area cooled, forming what we see today. That explanation, plus chemical clues inside the rock, suggests that the Isua supracrustal belt was once part of plate under the ocean, beginning around 3.8 billion years ago. "It's a fantastic case of solving a jigsaw puzzle ,"says one of the researchers. He notes that the puzzle was "a very difficult one because these rocks are all very old and have been badly ruined". 
 Question: What can we infer from the text? 
 Options: (A) The shapes of continents and oceans changed slowly. (B) The Earth's crust started shifting l.3 billion years ago. (C) The crust began to shift when the Earth was hot. (D) The hit from small planets made the Earth cool.
Solution:
A