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.
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Question: Background Paragraph: Carbon monoxide is used in modified atmosphere packaging systems in the US, mainly with fresh meat products such as beef, pork, and fish to keep them looking fresh. The carbon monoxide combines with myoglobin to form carboxymyoglobin, a bright-cherry-red pigment. Carboxymyoglobin is more stable than the oxygenated form of myoglobin, oxymyoglobin, which can become oxidized to the brown pigment metmyoglobin. This stable red color can persist much longer than in normally packaged meat. Typical levels of carbon monoxide used in the facilities that use this process are between 0.4% to 0.5%.
Story: Mike went to his local grocery store. He noticed that meats had two different packaging, product A and product B. When he looked closely, he found that in product A packaging carbon monoxide was used, but in product B carbon monoxide was not used. He asked the store clerk what difference it made.
Question: Would product A look red longer or shorter than product B?

Answer: longer.

Question: Background Paragraph: Storing large volumes of data When storing XML to either file or database, the volume of data a system produces can often exceed reasonable limits, with a number of detriments: the access times go up as more data is read, CPU load goes up as XML data takes more power to process, and storage costs go up. By storing XML data in Fast Infoset format, data volume may be reduced by as much as 80 percent.
Story: Carl had a busy day storing XML. At 1 PM, he stored 1000 Gigabytes to the database. At 2 PM, he stored 2000 Gigabytes to the database. At 3 PM, he stored 3000 Gigabytes to the database. At 4 PM, he got dinner. At 5 PM, he stored 4000 Gigabytes to the database. At 6 PM, he stored 5000 Gigabytes to the database. At 7 PM, he went to sleep to finish storing XML tomorrow.
Question: What time did storage costs go up: 3 PM or 7 PM?

Answer: 3 PM.

Question: Background Paragraph: Water stratification is when water masses with different properties - salinity (halocline), oxygenation (chemocline), density (pycnocline), temperature (thermocline) - form layers that act as barriers to water mixing which could lead to anoxia or euxinia.[1] These layers are normally arranged according to density, with the least dense water masses sitting above the more dense layers.

Water stratification also creates barriers to nutrient mixing between layers. This can affect the primary production in an area by limiting photosynthetic processes. When nutrients from the benthos cannot travel up into the photic zone, phytoplankton may be limited by nutrient availability. Lower primary production also leads to lower net productivity in waters.[2].
Story: Scientists studied water stratification in two saltwater lakes. they were trying to find out why the fish population decreased in Long lake, and was very healthy and abundant in Shoal lake. They found out the phenomenon occurred more often in Long lake, leading to very many unpleasant chain effects.
Question: Which lake had a smaller fish population?

Answer:
Long lake.