Generally, Only One Sperm Fertilizes an Egg Because

Generally, only one sperm fertilizes an egg because

A) sperm are so few that two are unlikely to arrive at the same time.
B) sperm compete against one another before entering, and only the most fit one is accepted.
C) one small entry hole called the blastopore allows only one sperm to fit through and then seals.
D) many sperm enter but only one set of chromosomes can fuse with the egg nucleus; the other sperm are absorbed.
E) when the first sperm membrane fuses with the egg membrane, it forms a fertilization membrane, which forms a barrier to the penetration of other sperm.