In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.

[EX Q]: Article: When policy experts debate climate change solutions, they often talk about "a price on carbon." They are arguing about whether companies should pay when they put carbon pollution in the air. Proponents say that it's simple economics -- if it's free to pollute, you'll get a lot of pollution. Opponents claim it will raise the cost of energy that's produced from high carbon sources, like coal. But here's the secret that most people seem to be missing: There already is a price on carbon, and it's paid by the taxpayers. Carbon pollution, like every other form of pollution, has an impact on the environment. Throwing waste into a river will cause the fish to die and the people who drink the water to get sick. And when you produce carbon pollution, you get climate change -- sea level rise, stronger storms, severe droughts, damage to agriculture, and more. All of those impacts cost money. Insurance rates go up when storms get more destructive. Taxes increase when cities have to rebuild bridges and roads. Military budgets go up when droughts and population changes cause conflicts. Not to mention impacts on agriculture and health care costs. In other words, the price on carbon is what we all pay when there is no market force to limit the pollution that causes climate change. So the debate is really about who will pay that price -- the companies who are making a profit from the fossil fuels, or the taxpayers who pick up the cost now? Right now, we have private profit and public cost. It's just like if we allowed every business to throw its garbage in the street because it's too expensive to have it moved away properly. Does it add a little bit to your dinner check to require that restaurants dispose of their trash properly? Sure. But it would be more expensive for you if the city had to clean the streets of their garbage every day. So just like we put a "price on garbage" we need a "price on carbon pollution." Now, a "price on carbon pollution" can mean a lot of things. You could tax companies based on the amount of carbon pollution they produce, and return the money to taxpayers. You could put a limit on how much they can produce, thereby requiring them to invest in ways to conduct business in a less polluting way.
Answer: Whether the companies should pay for it.
[EX A]: What do the policy experts argue about carbon pollution?

[EX Q]: Article: Imagination and fantasy can play an important role in achieving the things we fear. Children know this very well. Fred Epstein, in his book I Make It to Five, tells a story he heard from one of his friends about Tom, a four-year-old boy with a cancer in his back bone. He came through several operations and a lot of pain by mastering his imagination. Tom loved to pretend, and he particularly loved to play superheroes. Dr. Epstein explained that it was actually a brilliant way for his young mind to handle the terrifying and painful life he led. The day before his third trip to the operating room, Tom was terribly afraid. "Maybe I could go as Superman," he whispered to his mom. Hearing this, the mother hesitated for a while. She has avoided buying the expensive costume , but finally she agreed. The next day Tom appeared as the powerful Superman, showing off through the hospital halls and coolly waving his hand to the people greeting him along the way. And Tom, with the strength of his fantasy, successfully made it through the operation. The power of imagination need not be reserved for children only. We all have the power to use our fantasies to attempt things we never thought possible, to go through those things that seem impossible, and to achieve what we never believed we could. Just as Dr. Epstein puts it, "If you can dream it, you can do it." It doesn't mean that you should dress as a superhero for your next job interview. But, next time you are tested in a way that seems impossible, imagine what it would take to overcome it. Become the person you need to become to win over your challenge and do it in your mind first. So, let your imagination run wild, and dare to dream.
Answer: He was seriously ill.
[EX A]: What do we know about Tom?

[EX Q]: Article: A green roof is a roof of a building that is covered with vegetation over a waterproof membrane . It is a proper method of growing plants on the roof and does not refer to the mere green color of the roof. People benefit a lot from these green roofing systems, and they are gaining popularity day by day. Human beings have occupied major areas of land and transformed them into huge buildings, which has severely affected the environment and the natural habitat of bird and insects. Green roofing compensates for that. It creates a natural habitat for creatures like bees, grasshoppers and other insects. Modern roofs need a lot of energy to control the temperatures in winter and summer. However, green roofs reduce the amount of energy required for controlling temperatures, thus making them energy-efficient. As green roofing is highly energy-efficient, it can act as a encouragement for people who are interested in green roofing systems and their benefits. It will increase the market value of the building and fetch the owner a great share of profit. As the vegetation requires a water supply, there is a inbuilt water preservation layer in the green roof system. This layer helps to keep the rainwater. It makes full use of the rainwater and prevents wastage. During heavy rains, the water runs off the flat roof. The green roof prevents this overflow by slowing down the volume of running water. Green roofs can compensate for the lost greenery in urban areas and increase the artistic value of an area. Your building will look beautiful, coated with green vegetation. Green roofs can serve as local community garden and create a natural atmosphere, giving physical and psychological benefits like reducing stress levels in people and keeping them physically fit. Besides, people can start their own small-scale cultivation and experience the pleasure of gardening.
Answer: it is covered with grass, flowers or other plants
[EX A]:
What do we know about a green roof?