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.

[EX Q]: Background Paragraph: Iron is first oxidized to iron(II) ions by oxygen. In the second step, the iron(II) ions are further oxidized and combine with water and oxygen gas to produce a hydrated form of iron(III) oxide known as rust. Rusting is one of many example of corrosion. Corrosion is the deterioration of metals by redox processes. Corrosion causes enormous amounts of damage to buildings, bridges, ships, cars, and other objects. It has been estimated that corrosion costs the U.S. economy over 100 billion dollars each year. A great amount of time and effort is spent to try to limit or prevent corrosion. 
Story: Two neighboring cities had different climates. Dune city had very dry air and no rain, while Bay city had very high humidity, fog and lots of rain. 
Question: Which city had more problems with corrosion?
[EX A]: Bay.

[EX Q]: Background Paragraph: Active transport occurs when a substance passes through the cell membrane with the help of extra energy. This happens when a substance moves from an area where it is less concentrated to an area where it is more concentrated. This is the opposite of diffusion. The substance moves up, instead of down, the concentration gradient. Like rolling a ball uphill, this requires an input of energy. The energy comes from the molecule named ATP (adenosine triphosphate). The energy allows special transport proteins called pumps to move substances to areas of higher concentration. An example is the sodium-potassium pump. 
Story: Two cells, Cell B and Cell C, are being examined under microscopes by students in a science class. While looking at the cells, one student, Kim, notices that there is a noticeable trend in Cell B for a particular substance to try to group up in a more concentrated area. In Cell C though, she notices that the same substance is spreading apart and finding less concentrated areas to move to. 
Question: Which cell is not exhibiting active transport?
[EX A]: Cell C.

[EX Q]: 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 is smaller?
[EX A]:
Tripane.