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 Input: Article: How men first learned to invent words is unknown; in other words, the origin of language is a mystery. All we really know is that men, unlike animals, somehow invented certain sounds to express thoughts and feelings, actions and things, so that they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be combined to represent those sounds, and which could be written down. Those sounds, whether spoken, or written in letters we call words. The power of words, then, lies in their combinations - the things they bring up before our minds. Words become filled with meaning for us by experience; and the longer we live, the more certain words recall to us the glad and sad events of our past; and the more we read and learn, the more the number of words that mean something to us increases. Great writers are those who not only have great thoughts, but also express these thoughts in words which appeal powerfully to our minds and feelings. This charming and telling use of words is what we call literary style. Above all, the real poet is a master of words. He can convey his meaning in words which sing like music, and which by their position and association can move men to tears. We should therefore learn to choose our words carefully and use them accurately, or they will make our speech silly and rude.
Question: The origin of language _ .
Options: (A) is reflected in sounds and letters (B) is handed down from generation to generation (C) dates back to the prehistoric period (D) is a problem not yet solved
Example Output: D

Example Input: Article: Every day Yang Hongwei takes the bus home from work, staring silently at the European-style villas , luxury cars and twinkling lights from the shopping center that he sees through the window. Yang works for a software company in Zhongguancun. He dreams of such a life, away from poverty, and that hope has kept him in Beijing for three years since he graduated from university. Soon Yang squeezes his way off the bus to the reality of his life: his home--a 10-square-metre room that costs 550 yuan(81 US dollars) or about one-fifth of his salary in rent every month. It's very cold inside the house as it has no central heating system. He has to stand the long and cold winter. Determined to achieve his dream, Yang says he has changed jobs "numerous" times in the past three years and is considering quitting his present job. Yang's frustration over his life as a migrant is shared by many other graduates that have moved into big cities. Together they have come to be called the "ant tribe", a term created by Chinese sociologists to describe the struggles of young migrants, who, armed with their diplomas, flood to big cities in hopes of a better life only to put up with low-paying jobs and poor living conditions. They share every similarity with ants. They live in colonies in crowded areas. They're intelligent and hardworking, yet unknown and underpaid. The term, sociologists have said, also reflects their helplessness in a world governed by the law of the concrete jungle--only the strongest survive. A survey in Ant TribeII found nearly 30 percent of the "ants" are graduates of famous key universities--almost three times the percentage of 2009. Most have degrees in popular majors, such as medicine, engineering, economics and management. In addition, 7.2 percent of the "ants" have at least a master's degree compared to 1.6 percent in 2009. Most said the economic recovery did not really improve their financial situations, and 66 percent said their incomes fell short of their expectations, the survey also found. For two years, Lian Si, a post-doctoral fellow at the Center for Chinese and Global Affairs of Peking University, who has studied the phenomenon, led a team of more than 100 graduate students to follow the groups in university towns like Beijing, Shanghai, Guangzhou, Wuhan and Xi'an. Lian evaluates the total population of the "ant community" in major cities at one million across China, with about 100,000 found in Beijing alone. Lian predicts that an increasingly challenging job market will see the ant tribe growing further in number. Another 6.3 million graduates are expected to join migrant workers and other job hunters in what promises to be a fierce labour competition. The ant tribe's embarrassing living situations have become a serious social issue, and the government should develop "second-and-third-tier cities" to attract more graduates from big cities. However, "ants" expect more study and training opportunities in big cities, which keeps them in positive mindsets despite their situations. As in the case of Yang, he is optimistic about getting a new job soon, having received eight interview offers in a week after sending out his resume. The prospect of landing a higher-paying job keeps him hopeful of moving out of the slum district soon. The sooner the better.
Question: . Yang has worked in Beijing since graduation from university _ .
Options: (A) to live in a beautiful villa of European style (B) to have more opportunities to be promoted (C) to struggle for a better-off life in a big city (D) to enjoy a busy life in a software company
Example Output: C

Example Input: Article: Once upon a time the colors of the world started to quarrel. Green said, "Clearly I am the most important. I am the sign of life and hope. I was chosen for grass, trees and leaves. Look over the countryside and you will see that I am in the majority." Blue interrupted, "You only think about the earth, but consider the sky and the sea. It is the water that is the basis of life." Yellow chuckled . "The sun is yellow, as well as the moon and the stars. Every time you look at a sunflower, the whole world starts to smile." Red could bear it no longer. "I am the ruler of all of you. I am blood-life's blood! I am the color of danger and bravery. I bring fire into the blood. I am the color of passion and love." Purple stood at his full height. "I am the color of royalty and power. I am the sign of authority and wisdom. People do not question me! They listen and obey." Finally Indigo spoke with determination, "Think of me and I am the color of silence. I represent thought and reflection. You need me for balance and contrast , for prayer and inner peace." The colors went on boasting , each showing off his or her own advantages. Suddenlythere came a flash of bright lightening. Thunder rolled and boomed. Rain started to pour down. The colors were scared to death. In the midst of the quarrelling, rain began to speak, "You foolish colors. Don't you know that you were each made for a special purpose, unique and different? Join hands with one another and come to me." Doing as they were told, the colors united and joined hands. From then on, when it rains, colors will stretch across the sky in a great bow of color. Whenever a rainbow appears in the sky, let us remember to appreciate one another.
Question: Why did the colors quarrel?
Options: (A) Because they often fought for some reasons. (B) Because they were not liked by each other. (C) Because they all claimed to be the best. (D) Because they all wanted to rule other colors.
Example Output:
C