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: Hong Kong is one of the most densely populated cities in the world, but with night skies around 1,000 times brighter than globally accepted levels, it gains a bad reputation for its light pollution. A study by Hong Kong University found that brightness levels in the southern Chinese city's popular shopping district of Tsim Sha Tsui were 1,200 times greater than the international dark sky standard. The crowded city of 7 million residents , full or residential high-rises, towering office blocks and neon advertisements, has no laws to control outdoor lightning. The result is that light pollution is thought to be much worse than in other large cities, including London, Sydney, Tokyo and Shanghai. "In Hong Kong , you can't go anywhere outdoor in the evening without your eyes being blinded by this really disturbing outdoor lightning," the light pollution survey's head Jason Pum told AFP. "The fact that we have all this light in the sky means energy is wasted," he said, adding that too much artificial lightning also affects nightly wildlife. Research has suggested that light pollution can cause a number of harmful health effects in humans, including sleeplessness and headaches and can also interrupt body clocks and hormones . The university survey, the result of five million measurements taken from points across the city, was released just days before the start of the annual Earth Hour event, organized by the World Wildlife Fund. People around the world will be encouraged to turn off the lights for an hour on Saturday night to raise awareness of climate change. Last year, a number of Hong Kong's major buildings along Victoria Harbour went dark to mark Earth Hour. "Anyway, we should do our best to reduce the amount of lightning and adjust it for the benefit of the environment."
Question: If you walk out at night in Hong Kong, you can see all those things except _ .
Options: (A) neon advertisements (B) residential buildings (C) a dark sky with twinkling stars (D) high office blocks
Output:
C