What Is the Most Reasonable Explanation for the Recent Trend

What is the most reasonable explanation for the recent trend in dolphin numbers in the eastern Pacific,as shown in part (b) ?

A) Dolphins are not federally protected,and therefore their populations have not recovered.
B) Dolphin populations have not recovered because humans have caught much of their prey,reducing the number of fish that are available to eat.
C) Tuna fleets still catch a considerable number of dolphins as bycatch,so their numbers have not recovered.
D) Although dolphins are no longer being caught as bycatch,their populations have not recovered because fleets are now fishing for these dolphins.
E) Dolphin populations have not recovered because an Ebola -like pathogen has been decimating their populations.