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: New species develop naturally through the process of natural selection . Due to natural selection, organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers. Natural selection causes beneficial heritable traits to become more common in a population and unfavorable heritable traits to become less common. For example, a giraffe's neck is beneficial because it allows the giraffe to reach leaves high in trees. Natural selection caused this beneficial trait to become more common than short necks.
Story: A biologist was in Australia making observations about the local species when he identified two distinct groups of butterflies. He found that one group of butterflies, group A, blended in with the dark oak trees that were common in the area. Butterflies in the other group, group B, however did not blend in as well and could easily be spotted by predators whenever they landed on the oak trees.
Question: Will the traits belonging to the group A butterflies become more common or less common over time?
[EX A]: more common.

[EX Q]: Background Paragraph: In exercises such as weight lifting, skeletal muscle contracts against a resisting force (see Figure below ). Using skeletal muscle in this way increases its size and strength. In exercises such as running, the cardiac muscle contracts faster and the heart pumps more blood. Using cardiac muscle in this way increases its strength and efficiency. Continued exercise is necessary to maintain bigger, stronger muscles. If you don't use a muscle, it will get smaller and weakerso use it or lose it.
Story: Bill and Bob were two brothers. they were both into physical exercise, but Bill chose weight lifting, and Bob running.
Question: Which brother used his cardiac muscle in a less efficient way?
[EX A]: Bill.

[EX Q]: 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: Two sisters went to the hospital. The medics ran some blood tests and found out that Sue had sickle cell trait, while Mary had normal blood cells. Sue received treatment.
Question: Which sister has a genetic abnormality?
[EX A]:
Sue.