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.

[EX Q]: Background Paragraph: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution, acid rain, and global warming. Fossil fuels are also limited and may eventually run out. Like fossil fuels, radioactive elements are limited. In fact, they are relatively rare, so they could run out sooner rather than later. On the other hand, nuclear fission does not release air pollution or cause the other environmental problems associated with burning fossil fuels. This is the major advantage of using nuclear fission as a source of energy. 
Story: An alien passing by Earth in a UFO to write a report on two random cities so that his government can better understand what the people of Earth are like. He first flies over Nillmar, a city in France, which uses burns coal as its main production of electricity. After observing Nillmar, the alien flies over to Springfield, a city in the United States, that decided to use nuclear power to fuel itself. After taking his notes, the alien leaves and is eager to report back to his superiors about what he discovered. 
Question: Which city will need to change its method of electricity production sooner?
[EX A]: Springfield.

[EX Q]: Background Paragraph: If a zone undergoes dramatic changes in temperature with depth, it contains a thermocline. The tropical thermocline is typically deeper than the thermocline at higher latitudes. Polar waters, which receive relatively little solar energy, are not stratified by temperature and generally lack a thermocline because surface water at polar latitudes are nearly as cold as water at greater depths. Below the thermocline, water is very cold, ranging from −1 °C to 3 °C. Because this deep and cold layer contains the bulk of ocean water, the average temperature of the world ocean is 3.9 °C. 
Story: Keith was measuring the attributes of thermoclines. He selected two locations. One is near Miami, which is in the tropic. The other is near New York, which is in higher latitude. In total, he took four samples, sample A, sample B, sample C, and sample D. From Miami thermocline he took sample A. Then from below Miami thermocline he took sample B. From New York thermocline he took sample C. Finally, from below New York thermocline he took sample D. 
Question: Which thermocline would be deeper, sample A or sample C?
[EX A]: sample A.

[EX 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: Steven loves biking to get to and from places instead of driving his car. This weekend he is planning a long bike ride along the city streets to see some sites. He is however, concerned with traffic, and knows that it can sometimes be dangerous. He has wonder if he should travel with some friends for the ride, or just go alone. 
Question: Which would be the least crash prone way to travel for Steven?
[EX A]:
travel with some friends.