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.

Ex Input:
Article: One summer night Ludwig Beethoven took a walk in the suburb of Bonn. Suddenly a gentle wind came. He heard some music. He listened carefully and found it was his F sonata. He followed the music and came to a small house. There through the window, he saw a girl playing a very old piano and a young man was making shoes beside her, he pushed the door open and went in. The host received him very warmly and told him that the girl was his sister, who was blind but very fond of music. They couldn't afford to send her to a master. So she was only trying to play some music she heard the neighbors play. She knew it was the work of a great composer. Beethoven was very much moved. Suddenly the candle was blown out. Moonlight struck on the girl's slender figure. Then Beethoven played music for them. He played so wonderful that the brother and sister were amazed. That was his famous Clair de lune.
Question: Beethoven heard the music because _ .
Options: (A) it was played loudly (B) there was a slight wind (C) the piano was old (D) he stopped walking

Ex Output:
B

Ex Input:
Article: Winter begins in the north on December 22nd. People and animals have been doing what they always do to prepare for the colder months. Squirrels , for example, have been busy gathering nuts from trees. Well, scientists have been busy gathering information about what the squirrels do with the food they collect. They examined differences between red squirrels and gray squirrels in the American state of Indiana. The scientists wanted to know how these differences could affect the growth of black walnut trees. The black walnut is the nut of choice for both kinds of squirrels. The black walnut tree is also a central part of some hardwood forests. Rob Swihart of Purdue University did the study with Jake Goheen, a former Purdue student now at the University of New Mexico. The two researchers estimate that several times as many walnuts grow when gathered by gray squirrels as compared to red squirrels. Gray squirrels and red squirrels do not store nuts and seeds in the same way. Gray squirrels bury nuts one at a time in a number of places. But they seldom remember where they buried every nut. So some nuts remain in the ground. Conditions are right for them to develop and grow the following spring. Red squirrels, however, store large groups of nuts above ground. Professor Swihart calls " _ ". Gray squirrels are native to Indiana. But Professor Swihart says their numbers began to decrease as more forests were cut for agriculture. Red squirrels began to spread through the state during the past century. The researchers say red squirrels are native to forests that stay green all year, unlike walnut trees. They say the cleaning of forest land for agriculture has helped red squirrels invade Indiana. Jake Goheen calls them a sign of an environmental problem more than a cause.
Question: The study done by Rob Swihart and Jake Goheen is to _ .
Options: (A) find out the living conditions for squirrels (B) learn squirrels' influence on black walnut trees (C) do something to get rid of squirrels (D) save the forests in the American state of Indiana

Ex Output:
B

Ex Input:
Article: When I was a child I never said, "When I grow up, I want to be a CEO," but here I am. When I look back on my career, I realize the road to becoming a CEO isn't a straight, clearly clarified path. In fact, no two paths are the same. But whether you want to be a boss one day or not, there's a lot to learn from how leaders rise to the top of successful companies. As this series of stories shows, the paths to becoming a CEO may vary, but the people in that position share the qualities of commitment , work ethic and a strong desire for building something new. And every CEO take risks along the way--putting your life savings on the line to start a software company or leaving a big business to be one of the first employees at a startup. I grew up in Minnesota, and learned how to be an entrepreneur from my father, who has run a small business for almost 30 years. I went to Georgetown University and tried a lot of business activities in college with varying degrees of success. And I always had a dream job pattern: to walk to work, work for myself and build something for consumers. I'm only 29, so it's been a quick ride to CEO. Out of college, I worked for AOL as a product manager, then moved to Revolution Health and ran the consumer product team. In mid-2007 I left Revolution Health and started LivingSocial with several other colleagues, where I became a CEO. Career advice: Don't figure out where you want to work, or even what industry you'd like to work at. Figure out what makes you do so. What gives you a really big rush? Answer why you like things, not what you like doing...and then apply it to your work life. Also, just because you're graduating , don't stop learning. Read more books than you did in college. If you do, and they're not, you're really well in a position to succeed in whatever you do.
Question: According to the author, successful CEOs should _ .
Options: (A) try not to take risks (B) stay in the same business (C) have a strong sense of creativity (D) save every possible penny

Ex Output:
C