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: What is a common use of the mineral graphite?  
 (A) to make glass (B) as a source of iron (C) to make pencil leads (D) as a household cleaner

A: C
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Q: Which two body systems are involved in inhaling oxygen and exhaling carbon dioxide?  
 (A) endocrine and skeletal (B) excretory and nervous (C) circulatory and respiratory (D) digestive and reproductive

A: C
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Q: Harmful ultraviolet rays from the Sun are primarily absorbed by  
 (A) dust. (B) ozone. (C) land masses. (D) water vapor.

A:
B
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