instruction:
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.
question:
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 15 last week. On Saturday, there were 1551 motorcyclists. On Sunday, there were 2551 motorcyclists. On Monday, there were 3551 motorcyclists. On Tuesday, there were 4551 motorcyclists. On Wednesday, there were 5551 motorcyclists. On Thursday, there were 6551 motorcyclists. On Friday, there were 7551 motorcyclists. 
Question: What day had a lower crash rate per cyclist: Thursday or Friday?
answer:
Friday.


question:
Background Paragraph: One interesting thing that has been found in plants that are consistently exposed to drought, is their ability to form a sort of "memory". In a study by Tombesi et al., they found plants who had previously been exposed to drought were able to come up with a sort of strategy to minimize water loss and decrease water use. They found that plants who were exposed to drought conditions actually changed they way the regulated their stomates and what they called "hydraulic safety margin" so as to decrease the venerability of the plant. By changing the regulation of stomata and subsequently the transpiration, plants were able to function better in situations where the availability of water decreased. 
Story: Austria had two distinct climactic regions. The eastern region was exposed to a wet climate and had thriving vegetation, while the western region was exposed to drought. 
Question: Which region had more plants with an ability to change the way the regulated their stomates?
answer:
western.


question:
Background Paragraph: Mantle melting can come about three ways: (1) when the temperature rises, (2) if the pressure lowers (which lowers the melting point), and (3) if water is added, which lowers the melting point. Two of these (1 and 3) might explain why there are volcanoes at convergent plate boundaries the temperature of the subducting plate increases as it sinks into the hot mantle (1). Sediments lying on top of the subducting plate contain water. As the sediments subduct, the water rises into the overlying mantle material. This lowers the melting temperature of the mantle (3). When the mantle above the subducting plate melts, volcanoes form above it. This leads to volcanoes in an island arc or continental arc. 
Story: Two scientist, Pete and Gill, studied the Earth's crust and geology. Pete studied earthquakes, while Gill studied mantles and volcanos. 
Question: Which person studied more about sediments lying on top of the subducting plate?
answer:

Gill.