Select from the following.
(a). Greenhouse gases.
(b). rapid expansion.
(c). Burning fuel and air.
(d). permineralization.
(e). peachleaf willow.
(f). competition.
(g). unidirectional.
(h). food and shelter.

Fact 1: Gene flow occurs when individuals move into or out of a population. Fact 2: Gene flow between populations is unidirectional. Given the two facts above, what is individuals moving into or out of a population?
Answer:
(g).