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: Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the erosion and transportation of individual pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier". As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock. The freezing and thawing action of the ice enlarges, widens, or causes further cracks in the bedrock as it changes volume across the ice/water phase transition (a form of hydraulic wedging), gradually loosening the rock between the joints. This produces large pieces of rock called joint blocks. Eventually these joint blocks come loose and become trapped in the glacier. 
Story: Rob likes to visit high mountainous locations. Last year he visited the the Alps mountains in Austria. There he saw an unique type of glacier called valley glacier. This year he went further east to visit the Ural mountains in Russia. There he didn't see any valley glacier. 
Question: Which mountain would not see erosion of bedrocks?

A: Ural.
****
Q: Background Paragraph: Cholesterol has been implicated in heart disease for decades. Atherosclerosis is a disorder of the arteries in which cholesterol and other materials are deposited on the interior of the arterial wall. These deposits lead to the formation of plaques that can restrict or even block the flow of blood through these blood vessels (see Figure below ). A decrease in the flow of blood can lead to high blood pressure and a lowered oxygen supply to the heart muscle. A complete blockage of blood flow to parts of the heart (a heart attack) can cause significant damage due to oxygen deprivation, in some cases leading to death. 
Story: Two groups of patients were under observation for heart disease. The Red group was composed of people with low cholesterol, while the Yellow group was comprised of people with very high cholesterol. 
Question: Which group had fewer people with lowered oxygen supply to the heart muscle?

A: Red.
****
Q: Background Paragraph: The example of someone having a positive experience with a drug is easy to see how drug dependence and the law of effect works. The tolerance for a drug goes up as one continues to use it after having a positive experience with a certain amount the first time.[38] It will take more and more to get that same feeling. This is when the controlled substance in an experiment would have to be modified and the experiment would really begin. The law of work for psychologist B. F. Skinner almost half a century later on the principles of operant conditioning, "a learning process by which the effect, or consequence, of a response influences the future rate of production of that response.[39]. 
Story: The Angel Dusters met to discuss their experiences. They all said they always had a great experience using angel dust and used the same amount each time. They told how many times they used angel dust. Deon used it 10 times, Sang used it 20 times, Milford used it 30 times, Rosendo used it 40 times, Fritz used it 50 times, Jerold used it 60 times, and Napoleon used it 70 times. 
Question: Who has a higher tolerance for angel dust: Sang or Jerold?

A:
Jerold.
****