Answer:
c. Dichogamy
Step-by-step explanation:
Self-pollination is the fertilization of the male and female gametes from the same flower or from different flowers of same plant. Since the parent plant is same, there is not much genetic diversity in the gametes produced and it can be detrimental for the plant. To combat this problem, many plants engage in cross-pollination i.e. fertilizing male and female gametes are from different plants altogether.
Dichogamy is one of the methods to prevent self-pollination in bisexual plants (having both male and female flowers). Even though same plant has both male and female reproductive organs, they become mature and functional at different times. As a result, only one reproductive organ is functionally active at a time and can only propagate by mating with flower of another plant. This temporal barrier to self pollination is called dichogamy and its study comes under phenology i.e. seasonal natural phenomena with respect to plants and animals.