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: If a solution has a higher concentration of hydronium ions than pure water, it has a pH lower than 7. A solution with a pH lower than 7 is called an acid . As the hydronium ion concentration increases, the pH value decreases. Therefore, the more acidic a solution is, the lower its pH value is. Did you ever taste vinegar? Like other acids, it tastes sour. Stronger acids can be harmful to organisms. For example, stomach acid would eat through the stomach if it were not lined with a layer of mucus. Strong acids can also damage materials, even hard materials such as glass.
Story: In his chemistry lab David is learning about acids. He took three solutions to identify them correctly, sample A, sample B, and sample C. Sample A is a strong acid; sample B is a weak acid; and sample C is not an acid. David needs to identify the content of each sample by learning about their attributes.
Question: Which sample would most likely damage materials, sample A or sample B?

Output: sample A.

Input: Consider Input: 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: Gary had a lot of storing to do on his computer. At 1 PM, he stored 1 Gigabyte of XML data to the main file. At 2 PM, he stored 2 Gigabytes of XML data to the main file. At 3 PM, he didn't store anything. At 4 PM, he stored 3 Gigabytes of XML data to the main file. At 5 PM, he stored 4 Gigabytes of XML data to the main file. At 6 PM, he did nothing. At 7 PM, he got dinner. At 8 PM, he stored 5 Gigabytes of XML data to the main file. He went to sleep at 9 PM and had to start again in the morning.
Question: What hour did storage costs go up: 2 PM or 6 PM?

Output: 2 PM.

Input: Consider Input: Background Paragraph: Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk.
Story: Two neighboring habitable planets from the same solar system, planet U and planet N, had Earth-like atmospheres. The inhabitants of planet U destroyed the ozone layer by their actions, while their neighboring planet N didn't.
Question: Which planet released less bromine gas in their atmosphere?
Output: planet N.