Which determines carrying capacity?

it is determined by limiting factors for example if I had a small apartment I couldn't fit 50 people in there so the carrying capacity would be lower that that because of the limiting space.

Limiting factors.

Explanation:

Carrying capacity may be defined  the maximum number of individuals that can be supported by the environment without causing any problem to the environment. The population size increases below the carrying capacity and population size starts decreasing above the carrying capacity.

Limiting factors like food, surface area, water can limit the population growth. The absence of food may result in decline in the population. Hence, limiting factors determine the carrying capacity.

Thus, the answer is option (4).