You are given a science question (hard-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Q: Which situation would affect an organism's niche in a positive way?  
 (A) a decrease in livable habitat (B) a decrease in the normal temperature (C) an increase in the amount of prey available (D) an increase in the amount of competitors for food

A: C
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Q: Which of these is an environmental benefit of converting to solar energy?  
 (A) a decrease in air pollution (B) an increase in the cost of energy (C) an increase in the use of fossil fuels (D) a decrease in electrical energy production

A: A
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Q: In studying layers of rock sediment, a geologist found an area where older rock was layered on top of younger rock. Which best explains how this occurred?  
 (A) Earthquake activity folded the rock layers. (B) Volcanic eruptions destroyed a rock layer. (C) Erosion removed several layers of rock. (D) Weathering changed the layering of the rocks.

A:
A
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