In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

Q: the presence of which of these is required for the formation of cavernous chambers? (A) some carbonated soda (B) some carbon dioxide (C) some carbonic acid (D) carbon monoxide gas

A: C
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Q: This animal thrives while the sun is down (A) the bull shark (B) the snowy owl (C) the prairie dog (D) the spotted giraffe

A: B
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Q: This likely relies on a circuit being closed (A) your iPhone charger (B) your hair brush (C) your hat (D) your shoes

A:
A
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