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: The soldiers had just moved to the desert, and as they had never been in such a place before, they had a lot to learn. As there were no trees or buildings in the desert, it was, of course, very hard to hide their trucks from enemy planes. The soldiers were, therefore, given training in camouflage. They were shown how to paint their trucks in irregular patterns with pale green, yellow, and brown paints, and then to cover them with nets to which they had tied small pieces of cloth. The driver of the biggest truck had a lot of trouble camouflaging it. He spent several hours painting it, preparing a net and searching for some heavy rocks with which to hold the net down. When it was all finished, he went for lunch. When he came back from his meal, he was surprised and worried to see that his camouflage was completely spoilt by the truck's shadow, which was growing longer and longer as the afternoon advanced. He stood looking at it, not knowing what to do. Soon an officer arrived, and he, too, saw the shadow, of course. "Well," he shouted to the poor driver, "What are you going to do about it? If an enemy plane comes over, the pilot will at once know that there is a truck there." "I know, sir," answered the soldier. "Well, don't just stand there doing nothing!" said the officer. "What shall I do, sir?" asked the poor driver. "Get your spade and throw some sand over the shadow, of course!" answered the officer. 
 Question: From this passage you can know   _  . 
 Options: (A) there were a lot of trees where the soldiers were stationed (B) the soldiers were staying in an area far from the enemy planes (C) the soldiers knew nothing about desert (D) the soldiers had lived in desert before
Solution:
B