The Larvae of Some Insects Are Merely Small Versions of the Adult

The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following is most directly involved in the evolution of these variations in metamorphosis?

A) artificial selection of sexually immature forms of insects
B) changes in the homeobox genes controlling early development
C) the evolution of meiosis
D) the origin of a brain