Justification in the passage

Hi, This is a tough one- the next to last paragraph and the one before it seem to imply that this phenomenon still occurs (and since it seems like a pretty common, universal thing, we have no reason to think that it does not occur anymore), but this is never explicitly stated. However, I think the beginning of the final paragraph gives us the best support for E. It tells us that we know that something can prevent these landslides, which strongly implies that they still happen in the absence of vegetation.