A reaction of granules content which harden the zona pellucida and ensures sure block to polyspermy is ______________.
The correct option is C Cortical reaction
Immediately after the fusion of sperm and egg plasma membranes, the egg shows a cortical reaction. In this reaction, the cortical granules present beneath the egg's plasma membrane fuse with the plasma membrane and release enzymes between it and zona pellucida. These enzymes harden the zona pellucida, which now functions to block polyspermy.