The acrosome is a region at the head of a sperm cell that contains digestive enzymes.

• A. Diploid
• B. Estrus
• C. Acrosome
• D. Alleles

Answer: (C)

The acrosome is a cap-like region at the tip of the sperm head that stores digestive enzymes used to penetrate the egg’s protective layers during fertilization. This definition directly matches the concept being tested, making it the best choice. During fertilization, the acrosome reaction releases enzymes such as acrosin to digest the zona pellucida, allowing the sperm to reach and fertilize the egg. The other terms don’t describe this sperm structure: diploid refers to chromosome number, estrus is the female’s reproductive phase, and alleles are gene variants. Knowing about the acrosome helps explain how fertilization occurs, which is important in livestock breeding and semen evaluation.