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.

Input: Consider Input: Background Paragraph: The water level is seasonal, being lowered by about 10 feet (3.0 m) over the winter. The reservoir fills in the spring from snow melt and underground springs. The lake is usually at full level by late spring, but in the occasional years of low snow melt and low rainfall, it may remain up to several feet below its typical level. Water is let out of the lake in the fall so that ice will not damage docks and other structures around the lake. This also leads to excellent water quality, as a significant portion of the water is replaced every year.
Story: Alpine lake had low water levels this spring although the lake is usually at full level by late spring. Last year was a very wet year with lots of precipitation. Rangers were planning on letting water out of the lake in the fall so that ice will not damage docks and other structures around the lake. The water levels were high enough in the fall so they proceeded in lowering the water level by 10 feet..
Question: When are the lake water levels lower, during winter or during late spring?

Output: during winter.

Input: Consider Input: 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?

Output: Bay.

Input: Consider Input: Background Paragraph: Carbon dioxide is the most significant long-lived greenhouse gas in Earth's atmosphere. Since the Industrial Revolution anthropogenic emissions primarily from use of fossil fuels and deforestation have rapidly increased its concentration in the atmosphere, leading to global warming. Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid.
Story: Milton has just discovered two new planets while looking through his telescope. Luckily, he has invented a device that allows him to analyze far away planets from the comfort of his own home. He boots up the device and discovers that while these two planets are very similar, planet A has much more carbon dioxide in its atmosphere than planet B. While looking through his telescope, he is also able to see that there is the same race of intelligent creatures on both planets. Milton plans to write to his local observatory about his discovery.
Question: Is the amount of carbonic acid in planet B's oceans higher or lower than planet A's oceans?
Output: lower.