The Small Number of Trophic Levels Uniformly Found in Food

Multiple Choice

The small number of trophic levels uniformly found in food chains

A) can be explained by energy reduction up the trophic scale.
B) is due to the uniformly low energy base (primary productivity) of all ecosystems.
C) is a phenomenon for which ecologists do not yet have a satisfactory explanation.
D) is because there are few predatory organisms in the chain.
E) is a result of the greenhouse effect.