Interactions Between Proteins on the Surface of the Pollen Grain

Multiple Choice

Interactions between proteins on the surface of the pollen grain and on the surface of the stigma are necessary for fertilization to proceed.What is the correct sequence of events that follow this interaction?

A) growth of pollen tube,double fertilization,formation of sperm
B) formation of sperm,growth of pollen tube,double fertilization
C) double fertilization,growth of pollen tube,formation of sperm
D) formation of sperm,double fertilization,growth of pollen tube
E) growth of pollen tube,formation of sperm,double fertilization