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.

[Q]: Article: Ever tried taking smart drugs to perform better in exams? They certainly work. Before last summer's exam, a few of my mates, merely out of curiosity, took a considerable amount of Modafinil, a drug normally used for narcolepsy . Guess what? While I was feeling sleepy, bored by revision, my mates were more focused. Modafinil is a smart drug that gives a user a feeling of staying awake for hours. It also sharpens the mind, improves memory and helps problem-solving. But it does more than just keeping you awake. It disturbs your mental system, making you desperate to do what you are doing. You just don't want to do anything else but revise all the time non-stop. A recent study discovers that healthy people use smart drugs, like Modafinil, to get down to and complete tasks they have been putting off, because these tasks seem more enjoyable when taking these drugs. This might sound like what a stressed student desires. However, the pills have a range of side-effects. "At present no evidence shows that these drugs are safe in healthy people," as a medical expert puts it, "Ordering online, though easy, is a dangerous way to obtain drugs. You never know what you're actually purchasing. " In my experience, Modafinil changes people's behaviour too. Over those weeks my friends became different people--in turn aggressive, cold. Even eating became "a waste of time" and so did conversation. A BBC survey found that of those who had tried smart drugs before, 92% would do so again. My friends say they'd happily do so without considering the practice a form of cheating. I admit I was curious--but not enough to try it. Seeing the strange behaviour of other users, I feel a little bit upset and scary. Modafinil may promise to change your grades, but it might also change the way you act. Don't say you haven't been warned!
Question: According to the author, his mates took Modafinil for the purpose of _ .
Options: (A) escaping from reality (B) getting better exam results (C) curing their narcolepsy (D) leading an active life
[A]: B

[Q]: 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
[A]: D

[Q]: Article: Having one of those days--or weeks--when everything seems to annoy you? Even if you do nothing about it, your bad mood will probably go away after some time. But with a little effort, you can forget it much faster, often within a day or two. Walk it off Exercise is the most popular bad-mood buster. A person who's in a bad mood has low energy and high tension. Taking a fast ten-minute walk, or taking some quick exercise can do wonders towards changing that bad mood. Tune it out Listening to your favorite music for a while can also make tensions go away quickly, because music starts associations with past positive experiences we've had. Give yourself a pep talk Stop and listen to what's on your mind. Bad moods are often started by too many negative thoughts. Write them all down on paper, including the pessimistic messages you've been giving yourself and then give optimistic answers.("I still don't have a job." Vs" I have two interviews next week.") Reduce your stress Relaxation techniques are wonderful mood-lifters. There include de3ep breathing, stretching and visualizing, all of which sound complicated but aren't. One easy way to visualize, close your eyes and picture a favorite place, such as the beach. Another simple way to unhappiness is to make a to-do list. One reason for being in a bad mood is feeling you have no options. By taking control over certain areas, you realize you're not helpless. You can make changes in your mood and life. Avoid things that won't improve your mood TV may not help much: you need to increase your energy level and stimulate your mind-something that the TV show "Neighbors" won't do. And before you reach for that piece of cake and coffee, think about how mood and food are linked. Sugar and caffeine contribute to depressed moods. The better choice? Research shows that carbohydrates, such as potatoes and pasta , produce a calming effect on people who have a desire for them.
Question: Which of the following may help us stop a bad mood?
Options: (A) Draw a picture of something complicated. (B) Put more sugar into your coffee. (C) Writing down negative thoughts. (D) look ahead and write something positive.
[A]:
D