What is the theory that states organisms best adopted for an environment are more likely to survive and reproduce?

natural selection

Explanation:

According to Charles Darwin's theory of evolution by natural selection, organisms that possess heritable traits that enable them to better adapt to their environment compared with other members of their species will be more likely to survive, reproduce, and pass more of their genes on to the next generation.

option number one would be youre best option

true is the final answer!