Question

In the early 1900s, experiments were conducted on two caterpillar species. The members of the two species

Answer 1

The most likely answer to your question would be (3) gene expression being affected by the environment. 

This is the correct answer because these two species had each different environmental influences where one had enough light, the other didn't. Because this difference was apparent, the genetic potential that both of the species shared eventually manifested into something different. Intensely colored wings for some butterflies and paler wing colors for other butterflies.