3) once cells with nuclei developed, organisms were able to become more complex, which allowed them to adapt to the conditions in more habitats. by which process do organisms adapt and evolve? a) mitosis b) behavior c) mutation d) natural selection

Natural selection

Explanation:

Natural selection can be defined as the adaptation of the characters which helps organism in being more complex in organisation and more stable in environment.

The selection of the characters that makes it stable in environment is naturally selected. Example: Choosing long neck over short helps in getting leaves situated at higher heights.

Natural selection takes place in an organism when it undergoes mutation and mutation is favored by nature.