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.

Example Input: 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?
Example Output: southern.

Example Input: 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?
Example Output: not a cause of death.

Example Input: Background Paragraph: Saturated hydrocarbons are given the general name of alkanes . The name of specific alkanes always ends in – ane . The first part of the name indicates how many carbon atoms each molecule of the alkane has. The smallest alkane is methane. It has just one carbon atom. The next largest is ethane with two carbon atoms. The chemical formulas and properties of methane, ethane, and other small alkanes are listed in the Table below . The boiling and melting points of alkanes are determined mainly by the number of carbon atoms they have. Alkanes with more carbon atoms generally boil and melt at higher temperatures. 
Story: Scientists are studying two alkanes in a laboratory, Mophane and Tripane. Scientists are analyzing the various characteristics of these alkanes to be used in future scientific studies. They discover that Mophane has more carbon atoms than Tripane. This information will definitely be useful in the future!. 
Question: Which alkane has a lower melting point?
Example Output:
Tripane.