Given the task definition, example input & output, solve the new input case.
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
Output: B
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.

New input case for you: Article: When American inventor Alexander Graham Bell invented the telephone in 1876, it was a revolution in communication. For the first time, people could talk to each other over great distances. Over the last two decades a new means of spoken communication has appeared: the mobile phone. The mobile phone is like a two-way radio. But the two-way radio is a limited means of communication. As soon as the users move out of range of each other's broadcast area, the signal is lost. In the 1940s, researchers experimented with the idea of using a number of radio masts to pick up signals from two-way radios. A caller would always be within range of one of the masts. When he or she moved too far away from one mast, the next mast would pick up the signal. (Scientists referred to each mast's reception area as being a "cell". This is why in many countries mobile phones are called "cellphones".) However, 1940s' technology was just at the beginning. The "mobile phones" were huge boxes. They had to be moved by car. The first real mobile telephone call was made in 1973 by Dr Martin Cooper. As soon as his invention was complete, he tested it by calling a rival scientist to announce his success. Within a decade, mobile phones became available to the public. They have changed the way we do a lot of things. One powerful feature is: the short message service (SMS) or text message. It's the perfect communication method for the busy modern lifestyle. The text message has changed the way we write in English. The language construction became more lax . Traditional rules of grammar and spelling are much less important. Over the last few years mobiles have become more and more advanced. We have seen the introduction of cameras, global positioning system and Internet access. Alexander Graham Bell would be surprised if he could see how far the science of the telephone has developed in less than 150 years. If he were around today, he might say: '''That's gr8! But I'm v busy rite now. Will call U 2nite.'
Question: The article is intended to _ .
Options: (A) warn people of the possible risks in using mobile phones (B) inform readers of the history and benefits of mobile phones (C) convince people of the uses of mobile phones (D) predict the applications of mobile phones
Output:
B