Correct Option: D

Egg secretes fertilizin due to which acrosome of sperm secretes antifertilizin and due to their reaction sperm adheres to egg. The acrosome reaction is the reaction which occurs in the acrosome of the sperm as it approaches the zona pellucida. In mammals the acrosome reaction releases hyaluronidase and acrosin; their role in fertilization is not yet clear. It also alters a patch of pre-existing sperm plasma membrane so that it can fuse with the egg plasma membrane.