instruction:
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: Baker's yeast is the common name for the strains of yeast commonly used in baking bread and bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae,[1] and is the same species (but a different strain) as the kind commonly used in alcoholic fermentation, which is called brewer's yeast.[2] Baker's yeast is also a single-cell microorganism found on and around the human body. 
Story: the students used yeasts in two different experiments: they baked bread using baker's yeast, and made beer, using brewer's yeast. They learned a lot about sugars and chemistry. 
Question: Which yeast is better for bakery products?
answer:
baker's yeast.


question:
Background Paragraph: Air pollution is harmful to human beings and other living things. About 22 million people die from air pollution each year. Breathing polluted air increases the risk of developing lung diseases such as asthma and lung cancer. Breathing bad air also increases the chances of dying from other diseases. Children are most likely to be affected by air pollution. That’s because their lungs are still developing and growing. Children also take in more air for their size than adults do. Some air pollutants damage the environment as well as the health of living things. The type of damage depends on the pollutant. Air pollution can also harm the environment. 
Story: Two sister cities were part of an air pollution study. While Prague had big air pollution problems, Belfast was eco-friendly and its inhabitants were healthy. 
Question: Which city had fewer people with an increased chance of developing lung cancer?
answer:
Belfast.


question:
Background Paragraph: The Keystone XL Pipeline would transport oil from the oil sands in Alberta, Canada. The oil would travel into the United States. In the U.S. it would be refined. The pipeline is controversial. A leak could cause damage to wildlife habitat. A leak could also release enough oil to contaminate the Ogallala Aquifer. The Aquifer is crucial to agriculture and urban development in the Midwestern U.S. When burned, the fuel from the oil sands would increase pollutants. Greenhouse gases into the atmosphere would increase. The future of the pipeline is currently on hold. 
Story: Lawmakers were debating the pros and cons of Keystone XL Pipeline. One group of lawmakers proposed that the pipeline be constructed. They put their proposal in proposal A. The rival group of lawmakers proposed that the pipeline should not be build. They put their proposal in proposal B. Lawmakers would now have to choose one of the proposals. 
Question: Would proposal A hurt or benefit the wildlife habitat?
answer:

hurt.