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: A large log placed in a fire will burn relatively slowly. If the same mass of wood were added to the fire in the form of small twigs, they would burn much more quickly. This is because the twigs provide a greater surface area than the log does. An increase in the surface area of a reactant increases the rate of a reaction. Surface area is larger when a given amount of a solid is present as smaller particles. A powdered reactant has a greater surface area than the same reactant as a solid chunk. In order to increase the surface area of a substance, it may be ground into smaller particles or dissolved into a liquid. In solution, the dissolved particles are separated from each other and will react more quickly with other reactants. 
Story: Two friends went camping and made a fire each. Bill used a few large logs while Tim used kindlings, wood chips and sawdust. they both brought the same volume of wood. 
Question: Which friend didn't make a fire that burned faster?
Bill.

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 was a week long bike tournament. Day 1 had 500 cyclists left.  Day 2 had 400 cyclists left. Day 3 had 300 cyclists left. Day 4 had 200 cyclists left. Day 5 had 100 cyclists left. Day 6 had 50 cyclists left. Day 7 had 10 cyclists left. Tom won the tournament and got a big trophy. 
Question: What day had a lower crash rate per cyclist: Day 2 or Day 4?
Day 2.

Background Paragraph: Some individuals have a specific mutation in the primary sequence of their hemoglobin molecules that causes them to aggregate, resulting in a deformation of their red blood cells. This abnormality is genetic in nature. A person may inherit the gene from one parent and have sickle cell trait (only some of the hemoglobin is hemoglobin S), which is usually not life-threatening. Inheriting the gene from both parents will result in sickle cell disease, which is a very serious condition. 
Story: Dan studied two groups of individuals. Group S that had sickle cell anemia, and group B which had normal hemoglobin. He was fascinated by the results. 
Question: Which group had more members that had hemoglobin S?

Group S.