Acrosome reaction is triggered by:

Correct option is B

Correct Answer: (b)
Explanation:
The acrosome reaction is triggered after capacitation, a series of physiological changes sperm undergo in the female reproductive tract to become capable of fertilizing the ovum.
Information Booster:
Capacitation involves removal of cholesterol and glycoproteins from the sperm membrane.
This increases membrane permeability to Ca²⁺ and allows the acrosomal enzymes to be released.
The acrosome releases hyaluronidase and acrosin, which digest egg membranes for penetration.
The sperm then fuses with the oocyte plasma membrane to deliver the nucleus.
Successful acrosome reaction ensures monospermy and fertilization competence.
Additional Information (Incorrect Options):
(a) Lysin release occurs after acrosome reaction, not a trigger.
(c) Na⁺ influx affects motility, not acrosomal activation.
(d) Fertilizin (from egg) helps sperm binding, not the reaction trigger.