B.
Choices A and C should be able to be eliminated pretty quickly. Natural selection is where organisms ADAPT. In order for them to change THEY need to adapt to something DIFFERENT. The only thing the organism should be adapting to is the environment, therefore there should be a change in it. Choice D simply says that organisms only live in a change in environment when complex traits are in place, which simply isn’t true.
Imagine going back in history when giraffes were much shorter than what they are today. Their ENVIRONMENT had much more tall plants than smaller due to other organisms consuming them which led to the giraffe evolving into the tall animals we know today. Being as tall as they are today, those tall plants aren’t so high for them and allow them to get the nutrients and food they need.
