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: Sensing phantom phone vibrations is a strangely common experience. Around 80% of us have imagined a phone vibrating in our pockets when it's actually completely still. Almost 30% of us have also heard non-existent ringing. Are these signs of madness caused by digital culture? Not at all. In fact, phantom vibrations and ringing indicate a fundamental principle in psychology. Psychologists use a concept called Signal Detection Theory to guide their thinking about the problem of perceptual judgments. Working through the example of phone vibrations, we can see how this theory explains why they are a common and unavoidable part of healthy mental function. When your phone is in your pocket, the world is in one of two possible states: the phone is either ringing or not. You also have two possible states of mind: the judgment that the phone is ringing, or the judgment that it isn't. Obviously you'd like to match these states in the correct way. True vibrations should go with "it's ringing", and no vibrations should go with "it's not ringing". Signal detection theory calls these faithful matches a "hit" and a "correct rejection" But there are two other possible combinations: you could mismatch true vibrations with "it's not ringing" (a "miss"); or mismatch the absence of vibrations with "it's ringing" (a "false alarm"). This second kind of mismatch is what's going on when you imagine a phantom phone vibration. What does that mean in terms of your phone? We can assume that people like to notice when their phone is ringing, and that most people hate missing a call. This means their perceptual systems have adjusted their bias to a level that makes misses unlikely. The unavoidable cost is a raised likelihood of false alarms of phantom phone vibrations. The trade-off between false alarms and misses also explains why we all have to put up with fire alarms going off when there isn't a fire. It isn't that the alarms are badly designed, but rather that they are very sensible to smoke and heat and biased to avoid missing a real fire at all costs. The outcome is a rise in the number of false alarms. These are inconvenient, but nowhere near as inconvenient as burning to death in your bed or office. The alarms are designed to err on the side of caution.
Question: The writer tries to explain phantom phone vibrations_.
Options: (A) by analyzing some facts (B) by giving some examples (C) from the angle of biology (D) from the angle of psychology

Ex Output:
D

Ex Input:
Article: Ed Viesturs grew up in Rockford, Illinois, where the tallest thing on the horizon was the water tower. But on Thursday, Viesturs became the only American to climb to the top of the world's 14 highest mountains. His last hike was up Mount Annapurna, in Asia's snowcapped Himalayas. At 26,545 feet, its peak is the 10th highest in the world. It is the mountain that inspired him to start climbing. "It tends to be the trickiest, the most dangerous," said Viesturs. "There's no simple way to climb it. There are threatening avalanches and ice falls that protect the mountain." In high school, Viesturs read French climber Maurice Herzog's tale of climbing the icy Annapurna. Herzog's story was of frostbite and difficulty and near-death experiences. Viesturs was right away. Viesturs got his start on Washington's Mount Rainier in 1977, guiding hikes in the summer. Fifteen years ago, he set out to walk up to the world's highest peaks. Finally, he's done. The pioneering climber talks about mountains as if they were living creatures that should be treated with respect. "You have to use all of your senses, all of your abilities to see if the mountain will let you climb it," said Viesturs. "If we have the patience and the respect, and if we're here at the right time, under the right circumstances, they allow us to go up, and allow us to come down." What's next for a man who can't stop climbing? "I'm going to hug my wife and kids and kind of kick back and enjoy the summer," says Viesturs. But for a man who's climbed the world's 14 tallest mountains, he will probably soon set off on yet another adventure.
Question: What record has Ed Viesturs set?
Options: (A) He has succeeded in climbing to the world's 14th highest mountain. (B) He has been to the top of the world's 14 highest mountains. (C) He has become the first to climb to the height of 26,545feet. (D) He has become the first man to climb to the top of 14 highest mountains in the world.

Ex Output:
B

Ex Input:
Article: For many years people in Estonia have been leaving their rubbish in the forests. Rainer Nolvak, a businessman and his friends wanted to clean up all the rubbish in Estonia. The rubbish was not just an environmental problem. It was a problem of people's attitudes. Rainer Nolvak got together with a team of 20 friends and they began to make a plan about how to clean up the rubbish. Soon, over 600 people joined in the group. They named the project Let's Do It! Estonia. The Ministry of the environment gave them some support. Many other companies joined in the group. Famous actors and singers also took part. Even the President of Estonia joined in. They sent information about Let's Do It! Estonia throughout the country. Technology experts developed a special computer program. Team members went into the forests to find where the rubbish was. They used their mobile phones to mark every place where they found rubbish and send the information to the computer program. Then, the marked rubbish places appeared on the map. Anyone could go on the Internet and see the map. The team found a surprising result. There were over 10,000 tons of waste in the forests of Estonia. When people saw how much waste was around their own homes, they were shocked. Thousands of people began to help. The team chose May 3, 2008 as the day to clean up the rubbish. On May 3, more than 50,000 people helped to get rid of the rubbish. They moved over 10,000 tons of rubbish in only one day! This was amazing for the environment in Estonia. But it was also an important step for Estonian society. Rainer Nolvak gave a speech at a conference in the Balkans. He said: "The most important thing we did was build a team. It changed every one of us. We had to connect to people. We had to see that the rubbish was our problem. At times we are afraid of sharing. When we are together and there are many of us, we are not afraid.'
Question: The Project Let's Do It! Estonia is to _ .
Options: (A) prevent people leaving their rubbish anywhere (B) make Estonia a clean place (C) change people' s attitudes towards the environment (D) make plans for businessmen

Ex Output:
B