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: 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

Output: B

Input: Consider Input: Article: Three astronauts returned to Earth safely on Wednesday after a successful 15-day mission , marking another step forward towards the country's goal of building a manned space station by 2020. Zhang Youxia, commander-in-chief of China's manned space program, said the Shenzhou X mission was a "complete success". The Shenzhou X landed safely in north China's Inner Mongolia Autonomous Region at about 8:07 a.m. on June 26, 2013. All three astronauts were in good physical condition. Nie Haisheng, commander of the Shenzhou X crew and a second-time space traveler, was the first to get out of the bowl-like module , followed by Wang Yaping, the only female astronaut of the mission, and Zhang Xiaoguang. During a brief welcoming ceremony held at the landing area, the astronauts waved happily to a crowd consisting of officers, the search and recovery team, and health personnel. "It feels really good to be back home," said astronaut Nie Haisheng. "We are dreamers, and we have now realized our dream," said Zhang Xiaoguang. "Our space dream knows no limit, and our hard work will never stop," he said. Compared with its previous mission Shenzhou IX last year, the Shenzhou X is no longer experimental but considered an applicable shuttle system for sending astronauts and supplies to orbiting modules. The mission aims to further test technologies designed for docking and supporting astronauts' stay in space, as well as to use new technologies related to the construction of a space station. In its 15-day journey in space, Shenzhou X docked with the orbiting space lab Tiangong-1 twice, once through automatic operation and the other manual .The Tiangong-1 space lab has been in orbit for more than 600 days. It's designed to work for two years. The module is considered the first step in building a permanent space station in the future. And the astronauts spent 12 days in Tiangong-1, where they conducted space medical experiments, technical tests and gave a science lesson to students on Earth on June 19 about basic physics principles. The lecture was the second video class sent from space, with US astronaut Barbara Morgan's 25-minute class being the first in 2007. China is the third country after the United States and Russia to acquire the technologies and skills necessary for space rendezvous and docking procedures, as well as supply manpower and material for an orbiting module via different docking methods. Previous docking procedures conducted between Shenzhou-type spacecraft and the orbiting space lab included two automated dockings by the unmanned Shenzhou-8 in 2011 and both an automated and manual docking by the manned Shenzhou-9 in 2012. Since its first manned space space mission in 2003, China has sent ten astronauts and six spacecrafts into the space.
Question: According to the passage, the Shenzhou X _ .
Options: (A) was sent into space on June 11, 2013 (B) is still an experimental shuttle system (C) sent many supplies to the manned space station (D) returned to Earth safely on the afternoon of June 26

Output: A

Input: Consider Input: Article: Most people know Alexander Graham Bell invented the telephone. But not many know about another talking device (equipment) he invented just four years later, in 1880. He called the device the photophone. "Photophone" comes form the Greek words for "light" and "sound". The photophone did not use electricity to carry sound over wires between two people. _ . Instead, the photophone used a beam of sunlight traveling through the air. With his invention, Bell could actually transmit human speech on a beam of light. To do so, he spoke close to a thin mirror that was reflecting sunlight. The vibrations of his voice caused the mirror to vibrate, and the vibrating mirror caused the light to vibrate. The vibrating light hit a light-sensitive cell in a receiver placed some distance away. The cell changed the light patterns into electrical signals. Earphones changed the signals back into sounds. Bell believed that his idea of talking on a beam of light would prove to be important. He often called the photophone his greatest invention. Even though the photophone depended on a source of energy that was not constant--the sun--Bell wasn't a bit discouraged. He felt sure that people would one day talk using beams of light. Two much more recent developments made Bell's dream come true. In 1960, a scientist built the laser. A laser produces a highly concentrated beam of light. Shortly afterward, other scientists developed a new kind of optical fiber. The optical fiber is a glass thread. The new fiber could carry light beams long distances--as far as several miles.
Question: According to Bell's own opinion, _ is his greatest invention.
Options: (A) photophone (B) optical fiber (C) telephone (D) laser
Output: A