Which statement describes double fertilization in an angiosperm?

a. two egg cells are fertilized within each ovule.
b. a sperm nucleus fuses with an egg cell and a sperm nucleus fuses with polar nuclei.
c. two sperm are required for fertilization of one egg cell.
d. a flower can engage in both self-pollination and cross pollination.
e. one sperm fertilizes the egg while two polar nuclei fuse with a second egg.