Question

hardy - weinberg equilibrium can only occur if which of these conditions is met?
the population must be tiny.
random mating must not occur.
there must be no gene flow.

Explanation:

The Hardy - Weinberg equilibrium has several conditions. A large population (not tiny) is required to minimize genetic drift. Random mating is a condition (so "random mating must not occur" is incorrect). No gene flow (immigration/emigration) is one of the key conditions.

Answer:

There must be no gene flow.