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.
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
Example solution: B
Example 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.

Problem: Article: Today there are twenty to twenty-five million shopping carts rolling around the world.In fact,the shopping cart is presently one of the most often used items on four wheels,second only to the automobile.Indeed,almost everybody in America will spend a part of his or her life behind a shopping cart.They will,in a lifetime,push it many miles.But few will know-or even think to ask-who it was that invented them. Mr.Sylvan N.Goldman of Oklahoma City invented the shopping cart in 1937.Mr.Goldman's invention did not make him famous.It did,however,make him very rich.When Goldman invented the cart he was in the supermarket business.Every day he would see shoppers lugging groceries around in baskets that they had to carry.One day Goldman suddenly had the idea of putting baskets on wheels.The wheeled baskets would make shopping much easier for his customers.And by lightening their chore,he would attract their business.Pondering the idea,Goldman walked into his office and sat down on a folding chair.Looking down at the chair,Goldman had another idea.The carts,he realized,should be made so they could be folded up.This would make it easier to store them when not in use. On June 4,1937,Goldman's first batch of carts was ready for use in his market.He was terribly excited on the morning of that day as customers began arriving.He couldn't wait to see them using his invention.But Goldman was disappointed.Most shoppers gave the carts a long look,but hardly anybody would give them a try.After a while,Goldman decided to ask customers why they weren't using his carts."Don't you think this arm is strong enough to carry a shopping basket?"one offended shopper replied. Day after day,the same thing happened.People wouldn't use the carts.They preferred a basket on the arm to a basket on wheels.But Goldman wasn't beaten yet.He knew his carts would be a great success if only he could persuade people to give them a try.To this end,Goldman tried something that was both very clever and very funny.Believe it or not,he hired a group of people to push carts around his market and pretend they were shopping!Seeing this,the real customers gradually began copying the phony customers. As Goldman had hoped,the carts were soon attracting larger and larger numbers of customers to his market.But not only did more people come-those who came bought more.With larger,easier-to-handle baskets,customers unconsciously bought a greater number of goods than before. Today's shopping carts are five times larger than Goldman's original model.Perhaps that's one reason Americans today spend more than five times as much money on food each year as they did before 1937-before the coming of the shopping cart.
Question: The passage is written to .
Options: (A) tell about the life of an inventor (B) explain the power of advertising (C) introduce the history of an invention (D) analyze the secrets of business success
Solution: C