What primarily determines the carrying capacity of a population?

Correct Biotic and abiotic limitations

Carrying capacity is defined as the total number of an organism who can be supported in a given area within the natural resources limit and without harming or degrading the natural, economic or the cultural environment present for the future generations.

Carrying capacity is determined by the limiting factors, which are known to affect the natural resources available. It may include water, nutrients, minerals, space, light etc.

"a scientist studying a whale and its surroundings would need to understand the structure of atoms in case something was negatively affecting the whale or its surroundings."

explanation:

this was from the link provided:

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.