You are given a science question (easy-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 energy source is nonrenewable?  
 (A) sunlight (B) biomass (C) wind (D) fossil fuel

A: D
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Q: Which system of the human body provides protection to most of the major organs?  
 (A) skeletal system (B) circulatory system (C) respiratory system (D) muscular system

A: A
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Q: Water at 20 degrees Celsius is placed on a stove. As the water is heated, thermal energy is absorbed by the water. If the water is heated to a maximum temperature of 80 degrees Celsius, what happens as a result of the increased temperature?  
 (A) The potential energy increases. (B) The evaporation decreases. (C) The disorder decreases. (D) The entropy increases.

A:
D
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