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.

[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?
[A]: more common.


[Q]: Background Paragraph: Sand mining is a direct cause of erosion, and impacts the local wildlife.[2] Various animals depend on sandy beaches for nesting clutches, and mining has led to the near extinction of gharials (a species of crocodile) in India. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for organisms like coral that need sunlight. It can also destroy fisheries, financially harming their operators.

Removal of physical coastal barriers, such as dunes, sometimes leads to flooding of beachside communities, and the destruction of picturesque beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is often done illegally.[3] Globally, it is a $70 billion industry, with sand selling at up to $90 per cubic yard.[4]. 
Story: Sand mining in the north coastal region was stopped 20 years ago, but it still continues to this day in the south region. Both fishing communities there are still prosperous, but the southern one had a couple of bad years, with fish and other marine wildlife becoming more scarce. The southern beach had erosion problems as well. The northern beach recovered, and is suitable for tourism. 
Question: Which region has a higher water turbidity?
[A]: southern.


[Q]: 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: Greg is a doctor with the city hospital. Today, he is seeing two patients, patient A and patient B. Patient A maintains a high-fat diet, but patient B does not maintain a high fat diet. Greg is advising the patients how lifestyle change can improve their health. 
Question: Which patient would not have narrower arteries, patient A or patient B?
[A]:
patient B.