There Is a Limit to How Large Any Given Population

There is a limit to how large any given population can grow. Which of the following statements best explains why apopulation must eventually stop growing?

A) A low female-to-male ratio develops in the population as it grows.
B) Old individuals outnumber juveniles in the population as it grows.
C) The resources available are fully used by the population as it grows.
D) Natural selection changes the gene pool of the population as it grows.