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 unit of measurement describes an object's length?  
 (A) meter (B) kilogram (C) liter (D) degree

A: A
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Q: The systems of the human body work together. Which system works with the skeletal system by pulling on the bones to create movement?  
 (A) digestive (B) circulatory (C) muscular (D) nervous

A: C
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Q: A lizard in a desert sits on a warm rock. Where does the heat energy in the rock come from?  
 (A) the Sun (B) the lizard's skin (C) deep within Earth (D) the decay of plant materials

A:
A
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