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.
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Question: Background Paragraph: Gasoline-powered vehicles emit a lot of harmful materials. Nitrogen oxides are formed when atmospheric nitrogen reacts with oxygen at the high temperatures found in a car engine. Carbon monoxide is a by-product of incomplete combustion of hydrocarbons. Evaporated and unused fuel releases volatile hydrocarbons into the atmosphere to help form smog. The presence of a catalytic converter in the exhaust system of the car causes these materials to react and be changed into less harmful products. 
Story: Blue island and Red island were two big sister islands situated 100 miles from each other. People on Blue island used gas powered vehicles, while people on Red island used electrical vehicles. The people on Blue island presented more respiratory problems. 
Question: Which island emitted fewer harmful materials?

Answer: Red.


Question: 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?

Answer: Ben.


Question: Background Paragraph: Enzymes are proteins that increase the rate of chemical reactions by reducing the amount of activation energy needed for reactants to start reacting. Enzymes are synthesized in the cells that need them, based on instructions encoded in the cell’s DNA. Enzymes aren’t changed or used up in the reactions they catalyze, so they can be used to speed up the same reaction over and over again. Enzymes are highly specific for certain chemical reactions, so they are very effective. A reaction that would take years to occur without its enzyme might occur in a split second with the enzyme. Enzymes are also very efficient, so waste products rarely form. 
Story: Students in a high school chemistry class are conducting an experiment where they perform an acid-base reaction with various conditions. Half the students, called the non-enzyme half, perform the reaction by simply mixing the chemicals together and waiting. The other half of the students, called the enzyme-half, mix the chemicals together, then add an enzyme specialized for this specific reaction. 
Question: Which group will have to wait less for the reactions to finish?

Answer:
the enzyme-half.