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: Fish mortality is a parameter used in fisheries population dynamics to account for the loss of fish in a fish stock through death. The mortality can be divided into two types:

Natural mortality: the removal of fish from the stock due to causes not associated with fishing. Such causes can include disease, competition, cannibalism, old age, predation, pollution or any other natural factor that causes the death of fish. In fisheries models natural mortality is denoted by (M).[1]
Fishing mortality: the removal of fish from the stock due to fishing activities using any fishing gear.[1] It is denoted by (F) in fisheries models. 
Story: Bob works as a scientist for a large fishing company in Norway. Norway's government has strict regulations on fishing to protect its fish stock. Part of Bob's job is to provide the government with fish mortality data. Today, he has two samples of fish to investigate, sample A and sample B. Bob concluded sample A had natural mortality, but sample B had fishing mortality. 
Question: Would pollution be a casue of death or not a cause of death for sample B?

Answer: not a cause of death.


Question: 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 Salvia Squad met to discuss their experiences. They all said they always had a great experience using salvia and used the same amount each time. They told how many times they used salvia. Weston used it once. Jerrod used it a few times. Lucio used it a lot. 
Question: Who's tolerance is stronger for salvia: Weston or Jerrod?

Answer: Jerrod.


Question: Background Paragraph: Huge amounts of chemicals, such as fertilizers and pesticides, are applied to farm fields (see Figure below ). Some of the chemicals are picked up by rainwater. Runoff then carries the chemicals to nearby rivers or lakes. Dissolved fertilizer causes too much growth of water plants and algae. This can lead to dead zones where nothing can live in lakes and at the mouths of rivers. Some of the chemicals can infiltrate into groundwater. The contaminated water comes up in water wells. If people drink the polluted water, they may get sick. 
Story: Two farms were selling on Seattle markets. Berry farm, which used organic methods, no fertilizers and pesticides, and Rose farm, which used conventional agricultural methods, including fertilizers and pesticides. 
Question: Which farm contributes more to excessive algae growth?

Answer:
Rose.