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.

Input: Consider Input: Background Paragraph: Hepatitis B is a disease of the liver. It is caused by a virus called hepatitis B, which can be passed through sexual activity. Hepatitis B causes vomiting. It also causes yellowing of the skin and eyes. The disease goes away on its own in some people. Other people are sick for the rest of their lives. In these people, the virus usually damages the liver. It may also lead to liver cancer. Medicines can help prevent liver damage in these people. There is also a vaccine to protect against hepatitis B.
Story: Ben and Sam were two twin brothers. One day Ben was feeling sick so they went to the doctor and they discovered that Ben had hepatitis B. Sam was tested as well, but he was 'healthy as an ox'.
Question: Which brother experienced more yellowing of the eyes?

Output: Ben.

Input: Consider Input: Background Paragraph: It mutates DNA. The Chernobyl disaster was a nuclear accident that occurred on April 26, 1986. It is considered the worst nuclear power plant accident in history. A Russian publication concludes that 985,000 excess cancers occurred between 1986 and 2004 as a result of radioactive contamination. The 2011 report of the European Committee on Radiation Risk calculates a total of 1.4 million excess cancers occurred as a result of this contamination.
Story: In Arizona, there are two cities approximately 300 miles apart. Both of them have nuclear power plants in their town. Blinkton had a catastrophic meltdown at their nuclear power plant approximately 15 years ago. The city, Frafton, has a nearly identical nuclear power plant but has never experienced a nuclear accident before.
Question: Which city will have fewer people with cancer?

Output: Frafton.

Input: Consider Input: Background Paragraph: Predators play an important role in an ecosystem. For example, if they did not exist, then a single species could become dominant over others. Grazers on a grassland keep grass from growing out of control. Predators can be keystone species . These are species that can have a large effect on the balance of organisms in an ecosystem. For example, if all of the wolves are removed from a population, then the population of deer or rabbits may increase. If there are too many deer, then they may decrease the amount of plants or grasses in the ecosystem. Decreased levels of producers may then have a detrimental effect on the whole ecosystem. In this example, the wolves would be a keystone species.
Story: Dan and Joe studied animals for biology class. Joe had to study predator animals, while Dan studied herbivores and grazers.
Question: Which student learned more about rabbits?
Output: Joe.