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: There was no additional air in the tire the second time Lawrence checked the air pressure, but something did change between the two measurements. The tires had rolled over 10 miles of road on the trip to school. Any time one surface moves over another, it causes friction. Friction is a force that opposes the motion of two surfaces that are touching, and friction between two surfaces always generates heat. Quickly rub your hands together and you’ll feel the heat generated by the friction between them. As the tires moved over the road, friction between the tires and road generated heat. In short, the tires got warmer and so did the air inside them. 
Story: There was a carnival game at the fair that allowed you to win a basketball if you could correctly guess which of the two balls had spun around a circular track more times. Each ball would be dropped into identical circular tracks and then a curtain would cover them. Ball A would then spin around the track a certain amount of times, and Ball B would spin around a certain amount of times. After they were done spinning, you had to guess which ball completed more revolutions. A boy came up and had no idea how to figure out the answer, but when he picked them up he noticed that Ball A was slightly warmer than Ball B. 
Question: Which ball completed more revolutions?
answer:
Ball A.


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: 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 boiling point?
answer:

Tripane.