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: Supply and demand is perhaps one of the most basic concepts of economics and it is the backbone of a market economy. Demand refers to how much of a product or service is desired by buyers. The quantity demanded is the amount of a product people are willing to buy at a certain price; the relationship between price and quantity demanded is known as the demand relationship. Supply represents how much the market can offer. The quantity supplied refers to the amount of a certain goods producers are willing to supply when receiving a certain price. The relationship between price and how much of a goods or service is supplied to the market is known as the supply relationship. Price, therefore, is a reflection of supply and demand. The law of demand states that, if all other factors remain equal, the higher the price of a product, the fewer people will demand that product. The amount of goods that buyers purchase at a higher price is less as the price of a product goes up, so does the opportunity cost of buying that product. Like the law of demand, the law of supply shows the quantities that will be sold at a certain price. But unlike the law of demand, the supply relationship shows an upward slope. This means that the higher the price, the higher the quantity supplied. Producers supply more at a higher price because selling a higher quantity at a higher price increases the whole income. Now that we know the laws of supply and demand, let's turn to an example to show how supply and demand affect price. Imagine that a CD of your favorite band is sold for $20. Because the record company's previous analysis showed that consumers will not demand CDs at a price higher than $20, only ten CDs were sold because the opportunity cost is too high for suppliers to produce more. If, however, the ten CDs are demanded by 20 people, the price will then rise. As a result, the rise in price should cause more CDs to be supplied as the supply relationship shows that the higher the price, the higher the quantity supplied. If, however, there are 30 CDs produced and demand is still at 20, the price will not be pushed up because the supply is more than the demand.
Question: We know from the passage that changes in the prices of product cause changes in _ .
Options: (A) income and expense (B) invention and production (C) market and society (D) supply and demand

Ex Output:
D

Ex Input:
Article: Of all the famous English writers, probably the best known is William Shakespeare. He was born in Stratford-upon-Avon in 1564 on April the 23rd. His father was an important man in town so Shakespeare had a good upbringing. Shakespeare probably went to school (although no records survive to prove this) but not university. He got married when he was 18 to Anne Hathaway and the couple had 3 children. Shakespeare wrote 38 plays and 154 sonnets (a sonnet is a kind of poem). He began working in his home town of Stratford but by 1592 was writing in London. He became rich enough to buy a house in the capital and one in Stratford. He wrote sad stories called tragedies, like Romeo and Juliet, funny stories or comedies, romantic stories and stories about historical figures such as Julius Caesar. Shakespeare died on his birthday in 1616, almost 400 years ago. But why is his work still popular today? His work looked at common human themes, such as betrayal, murder, lust, power, ambition and love. These themes are as much a part of human nature today as they were all those years ago and are the themes we see in modern soap operas and Hollywood films. Even though his theatre, The Globe, burned down in 1613 it was rebuilt in London in 1997 and you can still see his plays performed there today. Shakespeare's influence on the English language can still be felt today. We talk about "fair play", meaning honest behaviour but this phrase was first used by Shakespeare. He coined the phrase "you can have too much of a good thing". And it was Shakespeare who came up with the expression to disappear "into thin air" which we still use today when we lose something. Shakespeare's work has been translated into every major language in the world. And perhaps we'll still be as fascinated by his work 400 years from now as we've been for the last 400.
Question: How old was Shakespeare when he died?
Options: (A) 18. (B) 28. (C) 49. (D) 52.

Ex Output:
D

Ex Input:
Article: Many of us use them several times a day without really noticing.And yet the way we in lifts,or elevators as they are known in the US,reveals a hidden anxiety. Passengers seem to know instinctively how to arrange themselves in an elevator,like the dots on a die.With each additional passenger, the bodies shift,going into the open spaces. On your own,you can do whatever you want--it's your own little box.If there are two of you,you take different corners, creating the greatest distance. When a third person enters, you will unconsciously form a triangle .And when there is a square, with someone I every corner.A fifth person is probable going to have to stand in the middle. Why are we so awkward in lifts? "You don't have enough space," says Professor Babette Renneberg, a clinical psychologist at the Free University of Berlin."Usually when we meet other people we have about an arm's length of distance between us. And that's not possible in most elevators, so it's a very unusual setting. It's unnatural." But perhaps there is more to it than just social awkwardness. "In the back of our minds we are a little anxious," says Nick White,an office in New York who was unfortunate enough to be trapped in a lift for41 hours. "We don't like to be locked into a place.We want to get out of the elevator as soon as possible, you know, it's a frightening place to be." During his terrible experience, he began to think of another encloses space-a tomb. Dr.Lee Gray agrees that a sense of disempowerment is the main cause of life anxiety. "You're in a machine that's moving, over which you have no control. You cannot see the elevator engine, you don't know how it's working," he says.
Question: Professor Babette Renneberg believes people feel uneasy in lifts because _ .
Options: (A) they can't move themselves (B) they cannot talk with one another (C) they have to stay too close together (D) they are afraid of accidents

Ex Output:
C