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: Turner et al (2006) derived crash prediction models for this report's predecessor and found a
pronounced 'safety in numbers' effect in the models. Using the crash prediction model for mid-block
locations, generic motorist and cyclist volumes can be used to demonstrate the impacts on the
expected crash rate of varying motor vehicle and cycle volumes. As shown in figure 2.20, an increase
in the proportion of cyclists to the overall traffic volume causes an increase in expected crashes at
mid-block locations, but the crash rate increases at a decreasing rate. That is to say, the crash rate per
cyclist goes down as the cycle volume increases.
Story: There were a lot of motorcycles on Interstate 4 last week. On Saturday, there were 1500 motorcyclists. On Sunday, there were 2500 motorcyclists. On Monday, there were 3500 motorcyclists. On Tuesday, there were 4500 motorcyclists. On Wednesday, there were 5500 motorcyclists. On Thursday, there were 6500 motorcyclists. On Friday, there were 7500 motorcyclists.
Question: What day had a lower crash rate per cyclist: Sunday or Friday?

A: Friday.
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Q: Background Paragraph: When the temperature of reactants is higher, the rate of the reaction is faster. At higher temperatures, particles of reactants have more energy, so they move faster. They are more likely to bump into one another and to collide with greater force. For example, when you fry an egg, turning up the heat causes the egg to cook faster. The same principle explains why storing food in a cold refrigerator reduces the rate at which food spoils (see Figure below ). Both food frying and food spoiling are chemical reactions that happen faster at higher temperatures.
Story: John just opened a coffee shop. He offers two types of coffee, coffee A and coffee B. In coffee A he mixes ingredients in hot water, but in coffee B he mixes ingredients in cold water. He also notices that his shop gets very busy in the morning, but during evening he doesn't have many customers.
Question: In which coffee the particles would move faster, coffee A or coffee B?

A: coffee A.
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Q: Background Paragraph: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution that harms the health of living things. The air pollution also causes acid rain and contributes to global warming. In addition, fossil fuels are nonrenewable resources, so if we keep using them, they will eventually run out. The main advantage of nuclear energy is that it doesn't release air pollution or cause the other environmental problems associated with the burning of fossil fuels. On the other other hand, radioactive elements are nonrenewable like fossil fuels and could eventually be used up.
Story: The U.S. produces its energy using fossil fuels, while Germany uses nuclear power plants as their main energy source. The two countries impact the environment in different ways.
Question: Which country contributes more to global warming?

A:
The U.S.
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