What is the most reasonable explanation for the variation in genome sizes across these living organisms?

Question

A. Higher order thinking and brain complexity are linked to genome size.
B. Genome size is controlled primarily by the size of the organism.
C. Animals have a larger genome size than plants.
D. Much of the DNA in a larger genome is not necessary for life.

Answer 1

B. Genome size is controlled primarily by the size of the organism.