Concept:Vasectomy is the surgical cutting of the male sperm duct to achieve permanent sterility.
Explanation:Sperm cells are produced in the testes.
They then pass through a coiled tube called the epididymis for maturation.
During ejaculation, sperm travel through a long muscular tube called the vas deferens.
The vas deferens, also known as the sperm duct, carries sperm from the epididymis to the urethra.
When this duct is cut or tied during a vasectomy, sperm cannot enter the semen.
Because sperm are blocked from reaching the female egg, fertilisation cannot occur.
This results in permanent sterility for the male.
In the given diagram, the labelled part that represents the vas deferens is part III.
Therefore, cutting part III will ensure permanent sterility.
Answer:C. III
