A vs. E

A tell us that if not acid, then beneficial, or If Not A -> B E tells us that they are beneficial only if not acidic, or If B -> Not A Under A, the waters could be beneficial if they are on fire, full of sharks, spikes, and turtle predators- as long as they are not acidic. Under E, we know that not acidic is needed for them to be beneficial, but lack of acid alone does not make waters beneficial.