Can someone explain this?

Hi Andrew, This is a weird setup. We are given a scenario where there is a strange paradox, that clouds seem not to be losing their oxygen 18 as they normally do. However, our job is not to explain the paradox, just to find something that we can prove. When going into the answer chicest I would keep an open mind and determine if there is anything we know must be true, even if it only seems tangentially relevant to the topic. A fits that. While it has little to do with the problem, it is more or less a restatement of the second sentence

Ah yes, I was trying to solve a paradox once I saw the discrepancy. I should've been more attentive to the question stem. Thank you.