I had this exact same confusion! It doesn't say that they always break apart, it says they tend to. So if it's true that one can be enough to sustain life, doesn't that strengthen the argument?

Wouldn't B also be wrong because we have no way of knowing from the stimulus what occurred before the past few decades? Like there could have been some even greater ecological issue?

I'm asking because that's the reason I eliminated it, and now I want to make sure I didn't do the right thing for the wrong reasons :)