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.

Background Paragraph: Although some lipids in the diet are essential, excess dietary lipids can be harmful. Because lipids are very high in energy, eating too many may lead to unhealthy weight gain. A high-fat diet may also increase lipid levels in the blood. This, in turn, can increase the risk for health problems such as cardiovascular disease. The dietary lipids of most concern are saturated fatty acids, trans fats, and cholesterol. For example, cholesterol is the lipid mainly responsible for narrowing arteries and causing the disease atherosclerosis. 
Story: Two groups of people were part of a science study. Group A ate lots of fats(lipids), while Group B  had a more balanced diet with few fats. Group A gained a lot of weight over the course of the 6 month study. 
Question: Which group had increased lipid levels in the blood?
Group A.

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 14 last week. On Friday, there were 1511 motorcyclists. On Saturday, there were 2511 motorcyclists. On Sunday, there were 3511 motorcyclists. On Monday, there were 4511 motorcyclists. On Tuesday, there were 5511 motorcyclists. On Wednesday, there were 6511 motorcyclists. On Thursday, there were 7511 motorcyclists. 
Question: What day had a lower crash rate per cyclist: Friday or Thursday?
Thursday.

Background Paragraph: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. The nitrogen is a fertilizer in the water bodies. Since there is a lot of nitrogen it causes algae to grow out of control. Figure below shows a pond covered with algae. Algae may use up so much oxygen in the water that nothing else can grow. Soon, even the algae die out. Decomposers break down the dead tissue and use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico. You can see it Figure below . 
Story: Our family was going to go fishing on Saturday. A few years ago we went fishing down the hill from a mushroom farm called Happy Pond. Since that time, there has been a lot of rain and we noticed Happy Pond had a green coating across the top of it. We also thought about going to a new pond in center of the park called Ridge Pond. We are hoping to catch a lot of fish to serve at our family reunion. 
Question: Does Happy Pond have more nitrogen or oxygen?

nitrogen.