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: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution that harms the health of living things. The air pollution also causes acid rain and contributes to global warming. In addition, fossil fuels are nonrenewable resources, so if we keep using them, they will eventually run out. The main advantage of nuclear energy is that it doesn’t release air pollution or cause the other environmental problems associated with the burning of fossil fuels. On the other other hand, radioactive elements are nonrenewable like fossil fuels and could eventually be used up. 
Story: The U.S. produces its energy using fossil fuels, while Germany uses nuclear power plants as their main energy source. The two countries impact the environment in different ways. 
Question: Which country contributes more to global warming?

A: The U.S.
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Q: Background Paragraph: Circadian rhythms are regular changes in biology or behavior that occur in a 24-hour cycle. In humans, for example, blood pressure and body temperature change in a regular way throughout each 24-hour day. Animals may eat and drink at certain times of day as well. Humans have daily cycles of behavior, too. Most people start to get sleepy after dark and have a hard time sleeping when it is light outside. In many species, including humans, circadian rhythms are controlled by a tiny structure called the biological clock . This structure is located in a gland at the base of the brain. The biological clock sends signals to the body. The signals cause regular changes in behavior and body processes. The amount of light entering the eyes helps control the biological clock. The clock causes changes that repeat every 24 hours. 
Story: Marcus has a long day ahead of him. He woke up early, around 7 AM to start his day. For a research study he takes his blood pressure around 9 AM and continues on through his day. Around noon he takes his blood pressure again noting that it has increased a little. He takes his blood pressure one more time before going to bed around 10PM. 
Question: Will an animals blood pressure be at its highest in the middle of the day or at its lowest?

A: highest.
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Q: Background Paragraph: Glaciers, while geographically restricted, are effective agents of landscape change. The gradual movement of ice down a valley causes abrasion and plucking of the underlying rock. Abrasion produces fine sediment, termed glacial flour. The debris transported by the glacier, when the glacier recedes, is termed a moraine. Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin.The way glacial processes interact with other landscape elements, particularly hillslope and fluvial processes, is an important aspect of Plio-Pleistocene landscape evolution and its sedimentary record in many high mountain environments. Environments that have been relatively recently glaciated but are no longer may still show elevated landscape change rates compared to those that have never been glaciated. Nonglacial geomorphic processes which nevertheless have been conditioned by past glaciation are termed paraglacial processes. This concept contrasts with periglacial processes, which are directly driven by formation or melting of ice or frost. 
Story: Two geologists were researching agents of landscape change. Danny studied glaciated environments, while Manny researched those that have never been glaciated. They later compared and exchanged data. 
Question: Which researcher studied more about plucking of the underlying rock?

A:
Danny.
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