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.

Input: Consider Input: Article: Nathan's second-hand bike was good enough to get him anywhere he wanted to go. Of course, it couldn't match Tim's in a normal speed race, but all the fancy gears in the world wouldn't get you up Black Mountain. It was so steep in places that you had to get off your bike and push. On this particular afternoon, the odds were all on Nathan's side. First, he was stronger. Tim had always been thin, but recently he'd started to grow so fast that his arms and legs were like pieces of spaghetti. As well as being considerably fitter than his friend, Nathan knew the shortcuts up prefix = st1 /BlackMountain. So when Nathan accepted the challenge, he was sure he'd win. He nearly always did, in competitions with Tim. That was what was strange. Tim was so competitive, and yet he wasn't any good at physical things. By the time the two boys were three quarters of the way to the top, Nathan was clearly ahead. While the road zigzagged back and forth up the mountainside, in certain places, there were also vertical tracks, where water rushing down the slope in winter had bitten erosion courses into the soil. These had in turn been so overgrown by bushes and long grass in the spring that they looked like tunnels through the bush. The trick was to know where you could cut off a whole bend in the road by leaving the road and pushing your bike up one of these half-hidden pathways. If you chose the wrong one you'd struggle up for ten minutes and then suddenly reach a dead end. Then there was no choice but to go back.
Question: What did Tim challenge Nathan to do?
Options: (A) test who had the fastest bike (B) decide who was the most competitive (C) find the secret tracks on the mountain (D) race to the top of BlackMountain

Output: D

Input: Consider 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.

Output: C

Input: Consider Input: Article: Steven Jobs was born on February 24,1955,in San Francisco,California,and was adopted by Paul and Clara Jobs.In 1961 the family moved to Mountain View, California.At that time people started to refer to the area as "Silicon Valley". As a child, Jobs preferred doing things by himself, not interested in team sports or other group activities.He enrolled in the HewlettPackard Explorer Club. There he saw his first computer at the age of twelve. He was very impressed, and knew right away that he wanted to work with computers. At that time almost all computers were so large that one could fill a room, and so costly that individuals could not afford to buy them.Advances in electronics, however, meant that the parts of a computer were getting smaller and the power of the computer was increasing. By 1980 the personal computer era was well underway.Apple was continually forced to improve its products to remain ahead, as more competitors entered the marketplace. Apple introduced the Apple III, but the new model suffered technical and marketing problems.It was removed from the market. Early in 1983 Jobs unveiled the Lisa.It did not sell well,however, because it was more expensive than personal computers sold by competitors.Apple's biggest competitor was International Business Machines (IBM). By 1983 it was estimated that Apple had lost half of its market share ( part of an industry's sales that a specific company has) to IBM. In 1984 Apple introduced a revolutionary new model, the Macintosh.The Macintosh did not sell well to businesses,however.It lacked features other personal computers had, such as a corresponding high quality printer. The failure of the Macintosh signaled the beginning of Jobs's downfall at Apple. Late in 1988 the NeXT computer was introduced, aimed at the educational market.The product was very userfriendly,and had a fast processing speed, excellent graphics displays,and an outstanding sound system.Despite the warm reception,however, the NeXT machine never caught on. It was too costly, had a blackandwhite screen, and could not be linked to other computers or run common software.
Question: When did Steven Jobs first get the chance to catch sight of a computer?
Options: (A) In 1955. (B) In 1961. (C) In 1967. (D) In 1980.
Output: C