Final answer:
Cortical granules stop implantation. After fertilization, the cortical granules release their contents, modifying the zona proteins to prevent sperm from binding and hardening the zona, forming a fertilization membrane.
Step-by-step explanation:
The cortical granules stop implantation. After fertilization, the cortical granules release their contents, including zonal inhibiting proteins and mucopolysaccharides, which modify the zona proteins. This modification prevents sperm from binding to the zona and also hardens the zona, forming a fertilization membrane that prevents further attachment or penetration of sperm. Therefore, the correct answer is b) Implantation; cleavage.