Given the task definition, example input & output, solve the new input case.
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.
Example: Article: Homework can put you in a bad mood , and that might actually be a good thing. Researchers from the University of Plymouth in England doubted whether mood might affect the way kids learn. To find out the answer, they did two experiments with children. The first experiment tested 30 kids. Someshapes were hidden inside a different, larger picture. The kids had to find the small shapes while sitting in a room with either cheerful or sad music playing in the background. To test their mood, the scientists asked the kids to point to one of five faces, from happy to sad. Children who listened to cheerful music tended to point to the smiley faces while the others pointed to the unhappy ones. The researchers found that sad kids took at least a second less to find the small shapes. They also found an average of three or four more shapes. In the second experiment, 61 children watched one of two scenes from a film. One scene was happy, and the other was sad. Just like in the first experiment, kids who saw the sad scene acted better compared to the others. The researchers guessed that feeling down makes people more likely to focus on a problem or difficult situation. Not all scientists agree with them, however. Other studies argued that maybe, that cheerful music in the first experiment distracted kids from finding shapes. While scientists work on finding out the answers, it still might be wise to choose when to do your tasks according to your mood. After eating a delicious ice cream, for example, write an essay. 
 Question: Researchers did experiments on kids in order to find out _ . 
 Options: (A) how they really feel when they are learning (B) whether mood affects their learning ability (C) what methods are easy for kids to learn (D) the relationship between sadness and happiness
Output: B
It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment. So, B is the correct answer.

New input case for you: Article: Life on Mars could become a reality and it could happen in your lifetime. A welcoming planet Scientists say Earth's neighbor Mars, a bright red planet about half Earth's size, is the most likely to support human life. Mars even has frozen water on its surface. Since the late 1990s, NASA has been exploring Mars using remote-controlled vehicles . Most recently Curiosity, a car-size vehicle, traveled through space on an unpiloted spacecraft  and landed on Mars in August 2012. Directed by NASA scientists , the vehicles move on the surface, taking pictures , collecting and analyzing soil, and looking for signs of life. But what about human explorers? Plans are already in the works to send astronauts to Mars as soon as the mid-2030s.  _  But before you start packing your bags, let's consider the challenges. For starters, Mars is far away. Just getting there could take up to 10 months. Scientists already know that time away from Earth's gravity harms the human body. Bones and muscles get weaker. The body produces less blood. What damage would months and months of living in space do? And then there is the matter of water, oxygen, food and fuel. Scientists will have to find solutions to these problems, or the first humans on Mars won't survive very long in their new home. Tiny Dangers There's another tinier risk. It's so tiny that you can't even see it: germs. Some scientists believe that our germs could pollute the whole planet of Mars. Potentially killing Martian life before we have the chance to discover it. Worse, there is a small but terrifying chance that any microscopic life already there might be harmful to us . Worse still, if any of those Martian germs  were brought back to Earth, the result could be disastrous. Animals, plants, and people could be wiped out. Worth the $$$? A more practical concern is the cost. The price could approach $ 1 trillion . How can we justify spending that much when so many problems--poverty, disease--could use the cash here on Earth? 
 Question: Which of the following is TRUE according to the "A welcoming planet" part? 
 Options: (A) Mars is a little bigger than Earth. (B) There are flowing rivers on Mars. (C) People haven't been to Mars so far. (D) Scientists have discovered signs of life on Mars.
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
C