Intraspecific competition limits a population size as

A. clumped distribution decreases competition, which removes weak and old individuals from the population
B. competition for resources intensifies as two different species compete for resources
C. certain alleles give some individuals a competitive advantage; less fit individuals are not as successful
D. K-selected species are more competitive than r-selected species, which changes natality and mortality rates

Hint: competition is a type of population interaction in which each species has a negative effect or harms the other in rivalry for food, space, water, oxygen etc...

I thought it was C, but I'm not sure...