Explanation for E

Hi Studying0, We are asked to explain a paradox here: that the Romans were aware of water power, but chose not to use it. E explains why they made this choice- because it would lead to unrest by causing unemployment. As to the how: the exact mechanism doesn't matter. E answers the question- it explains why the Romans made this choice. We don't really care about the exact trade-offs that this choice (like any choice) would entail.