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.

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?

A: Bay.
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Q: Background Paragraph: Human beings invented agriculture about 10,000 years ago. This provided a bigger, more dependable food supply. It also allowed people to settle down in villages and cities for the first time. Birth rates went up because there was more food and settled life had other advantages. Death rates also rose because of crowded living conditions and diseases that spread from domestic animals. Because the higher birth rates were matched by higher death rates, the human population continued to grow very slowly. 
Story: David was studying human history. He selected two specific eras of human history, era A and era B. Era A was before humans had invented agriculture. And, era B was after the invention of agriculture. He noticed that human societies had changed dramatically after the invention of agriculture. 
Question: Did era A have higher or lower brith rate than era B?

A: lower.
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Q: Background Paragraph: For example, if a circuit has a potential difference of 100 volts and it is intended for the circuit to contain a 100 ohm resistance, then the wires carrying the current for this circuit will be designed for 1.0 amp. If that 100 ohm resistance is suddenly cut out of the circuit and only 0.10 ohm resistance remains, then the voltage will push 1000 amps of current through the circuit. This current overheats the wires and may damage the circuits or start a fire in the walls or the appliance. There are many possible causes of a short circuit, one possible cause could be something overheating, melting wires, and thereby fusing the circuit closed, bypassing the resistance. Another cause might be something damaging the insulation of a wire, allowing the incoming and grounds wires to touch. In any case, once the resistance is lost, the voltage pushes a huge amount of charge through the wires causing them to overheat. 
Story: John is preparing for a do it yourself science project. First, he made a circuit with adequate resistance. He labeled that state of the circuit as circuit A. Then he lowered the resistance. He called that new state of the circuit as circuit B. While he was doing all this, his friend Keith showed up with another circuit, circuit C. But that circuit's insulation was damaged. 
Question: Which circuit would push lesser amount of charge through the wire, circuit A or circuit B?

A:
circuit A.
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