You are given a science question (hard-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 element makes up most of the air we breathe.  
 (A) carbon (B) nitrogen (C) oxygen (D) argon

A: B
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Q: Thomas Edison most likely invented the light bulb by using  
 (A) lit candles. (B) atomic models. (C) reflected light. (D) the scientific method.

A: D
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Q: The ability to roll the tongue in humans is coded by the dominant allele R. The inability to roll the tongue is coded by the recessive allele r. A man with an RR allele combination for the trait produces a zygote with a woman with an rr allele combination for the trait. Which allele combination could occur in the zygote?  
 (A) R (B) rr (C) Rr (D) RR

A:
C
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