Answer:
d. They are often keystone species
Explanation:
Top predators in an environment are the largest predators and sits on the top (apex) of the food chain in an ecosystem which do not have any natural predators.
As the top predators relative to its abundance has disproportionately large effect on its natural environment, they are the keystone species most of the time.
Hence option d. They are often keystone species is the right option.
I know this is a little late but i thought i should still tell you that its the endocrine organ
A physicist term for the measure of the amount of disorder is ENTROPY.
