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 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?
answer:
Thursday.


question:
Background Paragraph: Hepatitis B is a disease of the liver. It is caused by a virus called hepatitis B, which can be passed through sexual activity. Hepatitis B causes vomiting. It also causes yellowing of the skin and eyes. The disease goes away on its own in some people. Other people are sick for the rest of their lives. In these people, the virus usually damages the liver. It may also lead to liver cancer. Medicines can help prevent liver damage in these people. There is also a vaccine to protect against hepatitis B. 
Story: Dana and Sean both checked in as hepatitis B suspects, but only Sean had Hepatitis B. Dana was healthy and didn't carry the virus. 
Question: Which patient didn't experience yellowing of the eyes?
answer:
Dana.


question:
Background Paragraph: During late adulthood, the risk of developing diseases such as cardiovascular diseases and cancer continues to rise. Most people also have a decline in strength and stamina. Their senses may start failing, and their reflex time typically increases. Their immune system also doesn’t work as well as it used to. As a result, common diseases like the flu may become more serious and even lead to death. The majority of late adults develop arthritis, and as many as one in four develop Alzheimer’s disease. 
Story: Mike is studying the population growth rate of countries around the world. He noticed that countries like Japan and Russia are having a demographic shift. They have a growing population of late adulthood. He recorded the late adulthood population as population A. On the other hand, many developing countries have growing population of younger people. He recorded younger population as population B. 
Question: Which population would be less at risk of cancer or Alzheimer's disease, population A or population B?
answer:

population B.