Question

1. what kind of research did darwin do that led to his theory of evolution?

observations of plants and animals in many places
studying the genetics of different animals
experiments with animals in a lab
reading books about evolution

Explanation:

Darwin's theory of evolution was based on his extensive observations of plants and animals in various locations during his travels. He did not have access to modern genetic studies (which came later), nor did he conduct laboratory experiments in the way described. While reading might have influenced him, the key was his direct field - based observations.

Answer:

observations of plants and animals in many places