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: Haikou--A shark was killed after being dragged to shore at Yalong Berth beach in Sanya, South China's Hainan Province, on Sunday afternoon. It was the first time a shark had been caught in the beach area, a popular tourist site in Hainan. Local fishermen said they caught the 3-meter-long, l-ton shark by chance when they were fishing in sea water 1,000 metres deep near the beach. Police temporarily protected the shark while oceanographers decided whether it was a species belonging to State protection. Fishermen later killed and sold the shark after oceanographers _ that it was a whale shark and therefore not under State protection. The shark was believed to have drifted into the area from the deep sea due to strong waves caused last week by Typhoon Imbudo.It had no open injuries but experts said they believed it suffered from internal bleeding. Local police officer Fu Chenggeng said beachgoers should not feel threatened by sharks because the fish never attack human beings on their own initiative.Fu said he had never heard of any shark attacks at the Sanya beach since he first started work there eight years ago. However, police said they will improve the security system to safeguard tourists' safety on the beach.
Question: A possible title of the article should be _ .
Options: (A) Tourists in Danger (B) Killing Whale Shark (C) Shark Caught in Beach Area (D) Whale Shark in Danger

Ex Output:
C

Ex Input:
Article: VOIP stands for Voice Over Internet Protocol. It is also referred to as IP Telephony. It is another way of making phone calls, though the 'phone' part is not always present any more, as you can communicate without a telephone set. VOIP is especially popular with long distance calls. The main reason for which people are so massively turning to VOIP technology is the cost. VOIP is said to be cheap, but most people use it for free. Yes, if you have a computer with a microphone and speakers, and a good Internet connection, you can communicate using VOIP for free. There are basically three ways of using VOIP. One is to have a PC on both communicating sides; another is to have a phone on one side and a PC on the other and the third is to have two phones. VOIP is a ly new technology and it has already achieved wide acceptance and use. There is still a lot to improve and it is expected to have major technological advances in VOIP in the future. It has so far proved to be a good candidate for replacing the POTS (Plain Old Telephone System). It, of course, has drawbacks along with the numerous advantages it brings; and its increasing use worldwide is creating new considerations surrounding its regulations and security. The growth of VOIP today can be compared to that of the Internet in the early 90's. The public is getting more and more conscious of the advantages they can get from VOIP at home or in their businesses. Advertising campaigns, which are present everywhere on the net, are contributing a lot towards the popularization of VOIP which not only gives facilities and allows people to save, but also producing huge income for those who dived early into the new phenomenon.
Question: The author writes the passage mainly to _ .
Options: (A) ask readers to buy the new type of production. (B) tell us how fast the modern technology is developing. (C) introduce a new type of IP technology---VOIP. (D) teach the readers how to use VOIP.

Ex Output:
C

Ex Input:
Article: The immune system is the body's defender. It identifies, tracks down, and destroys troublemakers before they can hurt the body. Those troublemakers may be, for example, bacteria from a cut or splinter, a measles germ, a cold bug, or even a cancer cell. These invaders try to take over our tissues and feed off our bodies' nutrients. If they succeed, we become sick or, sometimes, even die. It's the job of our immune systems to destroy these invaders before they destroy us. Say you picked up a flu virus last week. Perhaps it entered your body through a cut, from a drinking glass, or from the air you breathe. Of course, you didn't feel it, but the virus made its way into your bloodstream. As soon as it entered your body, it began to reproduce. Viruses have only one goal: to take over your cells. Once inside your body, viruses try to enter cells and disrupt their normal work. If left alone, these viruses would hurt so many cells that you would weaken, or worse, get a serious illness. But this flu virus should not be so complacent as it seems to be. As it reproduces in your bloodstream, the virus is met by a certain kind of white blood cell, the lymphocytes. The _ are the foot soldiers that keep you alive. The number of lymphocytes in your body is hard to imagine. Thousands of them could fit in the period at the end of this sentence. Your body holds about a trillion --that's 1,000,000,000,000 of them, or about 3,000 in every drop of blood. _ Some of these lymphocytes pass through a small walnut-sized organ called the thymus. The thymus is the base of the neck. Here, special hormones turn lymphocytes into fighting cells, called T cells. T cells have one terrific talent: They can tell the difference between friend and foe; what should be in our bodies and what shouldn't. They do not affect the body 's healthy cells. Yet they attack everything that is foreign to our bodies, such as germs, transplants, and even our own cells which have become abnormal, as in the case of cancer.
Question: What is the function of our immune system?
Options: (A) To prevent bacteria or germs from entering the body. (B) To destroy the troublemakers in order that they might not hurt the body. (C) To fight against T cells. (D) To take over our tissues and feed off our bodies' nutrients.

Ex Output:
B