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: Prolonged exercise stimulates muscle cells to absorb sugar from the blood. This mechanism reduces stress placed on the body by signaling the body to produce  
 (A) insulin. (B) lipids. (C) hemoglobin. (D) hydrochloric acid.

A: A
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Q: A car runs out of fuel while traveling on a level road and eventually comes to a stop. Which of the following best explains why the car stops?  
 (A) Some of the energy of the car was lost to friction. (B) Some of the energy of the car was destroyed. (C) The amount of kinetic energy increased. (D) The amount of useful energy increased.

A: A
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Q: Parents with freckles often have children with freckles. This occurs because  
 (A) freckles develop from light. (B) certain foods cause freckles. (C) certain habits cause freckles. (D) freckles are an inherited trait.

A:
D
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