Some Orchids Grow Vegetatively and Flower Underground

Some orchids grow vegetatively and flower underground.However, since the biology of their gametophytes is typical for flowering plants, we can conclude that the male gametophyte

A) germinates within the anther.
B) is the pollen grain.
C) attaches to the ovule prior to germination.
D) can germinate on its own to form new plants.
E) is the macrogametophyte.