I believe it’s a or c. and those links are so annoying i had to start a new account
Answer - Theory
Reasoning - Your best bet and term to describe the evolution by natural selection is theory as to still scientific theory/research is still ongoing and changes can be made in a different direction.
<span>There are three major groups of mammals, categorized on the basis of their method of reproduction. Monotremes lay eggs to have children instead of having the mother bear them. The second type of mammal is the marsupial, which are non-placental animals who carry their young in their pouches. Eutherians are the third group who are placental mammals.</span>