Which of the following is a direct interspecific interaction?

A. Individual lions compete with each other for food and mates.

B. Through their effects on antelope behavior, lions increase the survival of some plant species.

C. Hormones circulating within a lion affect her levels of hunger and motivation to hunt.

D. Lions eat antelope; in the presence of lions the antelope population is reduced.

D. Lions eat antelope; in the presence of lions the antelope population is reduced.

Explanation:

Interspecific interaction refers to interactions which take place between multiple different species of organism. A refers to intraspecific interaction, which occurs between members of the same species. B does refer to interspecific interaction, but it is not direct, as it refers to the effect which lions cause by effecting antelopes. This is multiple steps of interaction, making it indirect - lion eats antelope which changes plant population. C refers to an interaction on the molecular level within one individual organism. D is direct interspecific interaction, as it refers to one species of organism directly changing another - lion eats antelope which changes antelope population.