Answer:
The correct option is A) The introduction of a plant variety that is resistant to insect pests.
Step-by-step explanation:
In ecological studies, gene flow can be described as the transfer of a genetic variant for of species from one population to another. It is also known as gene migration.
The phenomenon of gene flow allows to increase the genetic diversity of an area by the addition of a variant specie. This variant specie if favoured by natural selection will be able to survive and produces offsprings in the new area.