Concept:The human sperm cell has distinct parts: the acrosome (tip of the head), nucleus (head), mitochondria (neck), and tail.
Explanation:In the diagram, the part labelled I is the cap-like structure at the very tip of the sperm head.
This structure is called the acrosome.
It is not the nucleus, which is the main rounded mass inside the head.
It is also not the mitochondrion, which is found around the middle piece, nor the tail used for movement.
The acrosome contains enzymes such as hyaluronidase and acrosin that help the sperm penetrate the egg during fertilisation.
Thus, based on its position and function, the part labelled I is the acrosome.
Answer:A. acrosome
