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: A student hypothesizes that algae are producers. Which question will best help the student determine if this is correct?  
 (A) Do algae consume other organisms? (B) Which organisms consume algae? (C) Do algae use sunlight to make food? (D) Could an ecosystem survive without algae?

A: C
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Q: Divergent tectonic plate boundaries most commonly form  
 (A) ocean ridges. (B) ocean trenches. (C) non-volcanic islands. (D) continental mountains.

A: A
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Q: Why do mountain climbers at high elevations use oxygen tanks to help them breathe?  
 (A) At high elevations the ozone layer draws oxygen out of the atmosphere. (B) The atmosphere is less dense at higher elevations so there is less oxygen available. (C) Oxygen is heavier than the other gases in the atmosphere and sinks to lower elevations. (D) Radiation from the Sun splits oxygen molecules into atoms making the oxygen unbreathable.

A:
B
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