Speculate on the Diversity of Life on Earth If Plants

Speculate on the diversity of life on Earth if plants had never evolved.

A) The existence of large multicellular consumers like animals would be unlikely.
B) Since protists evolved before plants and can derive their energy by consuming bacteria, they could be expected to be common.
C) Bacterial life would be less diverse than it is presently.
D) All of the above are reasonable hypotheses.