You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You are also given a question about the story that requires an understanding of the relationship described in the background paragraph and the story. You need to come up with an answer to the given question; the answer will be a span from either the question or the story. In order to correctly answer the given question, you need to understand the relationship mentioned in the background paragraph and should be able to use it to understand that in the story. Your answer can not consist of any word that is not mentioned in any of these: the background paragraph, the story, or the question. You can directly copy and paste a span from the story or the question while answering the given question.

[Q]: Background Paragraph: Predators play an important role in an ecosystem. For example, if they did not exist, then a single species could become dominant over others. Grazers on a grassland keep grass from growing out of control. Predators can be keystone species . These are species that can have a large effect on the balance of organisms in an ecosystem. For example, if all of the wolves are removed from a population, then the population of deer or rabbits may increase. If there are too many deer, then they may decrease the amount of plants or grasses in the ecosystem. Decreased levels of producers may then have a detrimental effect on the whole ecosystem. In this example, the wolves would be a keystone species. 
Story: Two students studied animal behavior for the biology class. Ned studied more about predators, while Kim studied more about herbivores. 
Question: Which student studied less about keystone species?
[A]: Kim.


[Q]: Background Paragraph: Artworks are sold at affordable prices [6] ranging from £5 to £1500. For many of the works, the price goes up as the edition sells out. The edition runs range from 30 to 10,000 editions. Each work comes with a digital certificate that is “signed, numbered and authenticated by the artist” [7][8] Once an edition is sold out, collectors can resell their works in the online marketplace. 
Story: The prices of John's paintings started to rise immediately after the edition sold out. they used to cost $10 but now they sell for at least $200. john had 45 paintings in this edition. The prices of Mike's paintings are at $8 a piece, because his edition hasn't sold out yet. Mike's edition run was 250 editions. 
Question: Which paintings sell for more money today?
[A]: John's.


[Q]: Background Paragraph: Regions on the Earth's surface (or in its atmosphere) that are high above mean sea level are referred to as high altitude. High altitude is sometimes defined to begin at 2,400 meters (8,000 ft) above sea level.[5][6][7]

At high altitude, atmospheric pressure is lower than that at sea level. This is due to two competing physical effects: gravity, which causes the air to be as close as possible to the ground; and the heat content of the air, which causes the molecules to bounce off each other and expand.[8]. 
Story: There was a competition for who can get their yellow drone the highest into the air. Team 7 got it 3,335 ft. Team 8 got it 4,445 ft. Team 9 go it 5,565 ft. Team 10 got it 6,645 ft. Team 11 got it 11,635 ft. Team 12 got it 14,875 ft. Team 13 got it 15,895 ft. 
Question: What team got their drone into high altitude: Team 7 or Team 13?
[A]:
Team 13.