Water vapor evaporated from the ocean contains a greater proportion of oxygen 16 and a smaller proportion of the heav...

Julie-V June 19, 2019

Answer Choices B and C Clarification

After reading the discussion board, I have a better understanding as to why B is the correct answer. However, the word "increased" still makes the answer choice a little difficult to accept. Basically, the reason why o18 in seawater increased is because the evaporated o16 isn't cycling back into the ocean? Also, the explanation for C is still a little fuzzy to me. We eliminate C because there is not enough support to conclude that the concentration of o16 doesn't change during the interglacial period? Any help would be greatly appreciated, thank you in advance!

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shunhe January 9, 2020

Hi @Julie-V,

Thanks for the question! (C) is wrong because we aren't told anything about how much oxygen is in the rain and snow. (B), however, is correct because we know that the o18 in seawater doesn't leave the ocean as quickly, and since what leaves the ocean isn't coming back, the concentration of o18 is increasing overall. Hope this helps!