Answer the following question: Fact 1: Plants are the major producers in terrestrial biomes. Fact 2: Terrestrial biomes are defined by their plant life. Given the two facts above, plants are the major producers in biomes defined by their what?

Options are:
(I) the environment.
(II) competition.
(III) plant life.
(IV) animal life.
(V) heat produced.
(VI) vegetation.
(VII) water life.
(VIII) plant sources.
Answer:
(III)