Which of these is one of the conditions for hardy-weinberg equilibrium?

a. only some organisms can reproduce.
b. mutation cannot occur.
c. the population must be small.
d. organisms must choose mates.

The correct answer is -

B. Mutation cannot occur.

Hardy-Weinberg Principle/equilibrium decribes that the frequency of gene variant (allele) and genotype in a particular population remains constant over generation when there is no other evolutionary influences on the population.

There are following assumptions according to this principle -

1) There should be no mutation.

2) No natural selection should act upon the population.

3) Population size should be large.

4) There should be random mating

5) No gene flow that is immigration or emogration.

Thus, option B) is the right answer.