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.

Article: Oyster What is an Oyster card? Oyster is the easiest way to pay for journeys on the bus, Tube, tram, Docklands Light Railway (DLR), London Overground and National Rail journeys in London. You can store your travel cards, Bus&Tram Pass, season tickets and credit to pay for journeys as you go. Where to get an Oyster card? There are a number of ways for you to get an Oyster card: * At over 3,900 Oyster Ticket stops * At Tube and London Overground station ticket offices * At some National Rail stations * At London Travel information Centres * Online at tfl. gov. uk/oyster How to use an Oyster card? To pay the correct fare on the Tube, DLR, London Overground and National Rail services, you must always touch in on the yellow Oyster card reader at the start of your journey, and touch out at the end. If you don't, a maximum cash Oyster fare will be changed. When using the bus or tram, you must only touch in at the start, but not at the end of your journey. What happens if I don't visit London very often? Don't worry. Any pay as you go credit on your card will not expire , so you can keep it for your next visit or lend it to a friend. Fares Traveling by Tube from Central London (Zone l)to Heathrow (Zone 6) Adult Oyster single fare PS 4. 20 Monday to Friday 06:30 - 09:30 and 16:00 -19:00 PS 2. 70 at all other times including public holidays Adult single cash fare PS 5.00 For further information, visit tfl.gov. uk /fares.
Question: Which of the following is TRUE about Oyster cards?
Options: (A) They are limited in use to the owners themselves. (B) On National Rail services you must touch them on the reader twice. (C) They are not suitable for those who don't visit London often. (D) Oyster card Tube fares cost more on public holidays than on weekdays.
B

Article: Most middle school students find it boring to learn math. But students in Yet Sen Middle School in New York, US, don't think so. Why? Because they are in the school of One Program, which asks students to work on their own or in small groups on computers to have math lessons. "The program gives the students a new learning style. No traditional classroom can compare with it. We give each lesson according to the students' interest and their strong and weak points, "said Joel. Klein, the school's headteacher, "We're looking for a new way that interests students. " Students enjoy these math lessons, especially lessons with video games. They must find out the answers to math problems to get through the game. One such game is Dimension M. As students move through mazes with their keyboards, some questions come up. Caleb Deng had to answer the question: What is 5+(6x3)? He _ on paper quickly because there was just a minute left to play. "I was right, "said Deng, 14, as he ended the game with a high score . "This really makes math lessons more exciting, since we are fighting to learn better. "
Question: Students in Yet Sen Middle School like math because _ .
Options: (A) they work in large groups (B) they can work on computer (C) the teachers are interesting (D) math questions are easy there
B

Article: I went to the Chinatown market in London last Sunday. The first thing I did was to go to one of the Chinese green grocers' shops. As soon as I entered the shop, I smelt mixtures of Chinese spices and saw the new season's fruits. My son wanted a bag of sweets, so we popped into the shop next door which sells many kinds of candy. There's a lot of noise in the Chinatown market and you will see many tourists too. There are a lot of cars and trucks that never stop beeping. While people are loading and unloading their goods, most of them have their cars and trucks parked in the middle of the road. This causes great inconvenience for other drivers. Can you imagine that? After we had done all our shopping, my son and I went to a restaurant for lunch. We enjoyed our meal very much. But the shopping made us both very tired at the end. We headed down the road to catch our bus home. My son and I enjoyed riding in the bus. We also enjoyed looking at different buildings and people walking by dressed in fancy outfits. Although Chinatown can be a busy place to shop, I do enjoy going there now and then. I can buy some of my necessities, and I can also look and browse around the other shops and department stores where I can indulge myself with some nice things. Chinatown is located in the heart of central London where you can find tons of shops and other places to amuse you. And for me, I certainly don't mind going back there again soon.
Question: The author probably didn't go to a _ .
Options: (A) restaurant (B) grocery (C) clothing store (D) sweets shop
C