In sea urchins, the "fast block" and the longer lasting ...

[sammy]

In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are
A) the acrosomal reaction and the formation of egg white.
B) the cortical reaction and the formation of yolk protein.
C) the jelly coat of the egg and the vitelline membrane.
D) membrane depolarization and the cortical reaction.
E) inactivation of the sperm acrosome.

[Yolanda]

For sure it has to be D Mark as solved once you're done!