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.
One 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
Solution is here: B
Explanation: 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.

Now, solve this: Article: Scientists are developing the next generation of robot-driven cars and predict they could be carrying humans around by the year 2030.     The first wave of intelligent robot cars, capable of understanding and reacting to the world around them, will be tested this November in a competition run by the US Defense Advanced Research Projects Agency.     Scientists are developing vehicles which will not only be driven by robots independently, but will be able to operate in a complicated city environment. "In the past it was  _ for a vehicle just to perceive the environment," said Sebastian Thrun, a professor at Stanford University.   "The new challenge will be to understand the environment. The robot must be able to recognize another car, to understand that it is moving and that it will interact with it as it gets closer."  Stanford's entrant  "Junior" is a changed 2006 Volkswagen Passat whose steering, throttle   and brakes all have been modified by engineers.    Lasers fitted on the car bumpers, radar and global positioning systems feed data into the on-board computer to determine its location and position. Thrun predicted that advances in artificial intelligence would lead to driverless cars on the roads by 2030.    "Today they can drive about 100 miles, by 2010 I expect this to go 1,000 miles, by 2020 up to a million miles," he said. "By 2030 you'll be able to see them on the highway, with driving reliability that will beat humans."    "We believe this technology will affect all of us. It is going to have enormous significance for people who can't drive because of disabilities or because they are ill or impaired." Thrun said he believed robot-driven vehicles would be deployed in war zones before they were seen in everyday civilian environments. 
 Question: Compared with the old robot-driven cars, the new ones   _  . 
 Options: (A) can understand orders from humans (B) can perceive the environment dearly (C) are modified to be completely computer-controllable (D) not only can understand the environment but also can react to it
Solution:
D