First off, I’d say it’s a particularly tough question instead of a poorly written one
It requires knowing what would be considered very specific advanced vocabulary - morphology
But outside of that, it also requires very careful reasoning
I’d say based on your understanding of Greg’s explanation there you’re considering two answers, C and E
C is incorrect simply because the option doesn’t give us a “morphological” focus.
You’re correct in saying that diving deeper could have some level of morphological basis, however in most cases it’s due to training.
Without the outside knowledge of what diving requires however, simply the fact that it could be either or disqualifies it as the answer.
We would have to assume it’s morphological not behavioural. Once you have to assume, it’s incorrect.
E is the only option that references a morphological characteristic i.e In this case the bodily structure - the lung
(The argument could be made that A refers to a morphological characteristic but it’s disqualified because it is then compared to a behavioural one)