Infection of Potato Crops by the Fungus Phytophthora Infestans Is

Infection of potato crops by the fungus Phytophthora infestans is a constant menace to farmers. A biotechnological approach to prevent the recurrence of such an infestation is:

A) cloning of a wild potato gene that conveys resistance to P. infestans into commercial potato breeds
B) frequently spraying potato plants with fungicide throughout the growing season
C) watering plants with a trickling mechanism to avoid excessive dampness
D) all of the above
E) none of the above