What is the procedure known as circumcision?

Circumcision is defined as a surgical procedure specifically aimed at removing the foreskin of the penis. This foreskin is the retractable fold of skin that covers the glans, or head, of the penis. The procedure is often performed for various reasons including medical, cultural, or religious practices.

It's important to understand that in the context of this question, the other options describe entirely different medical procedures. Removing the testicles is known as orchiectomy; surgical alteration of the vagina could refer to various gynecological surgeries, such as vaginoplasty, and is unrelated to circumcision; and inserting a catheter into the bladder describes a catheterization procedure, which also has no relation to circumcision. Thus, option A accurately encapsulates the definition and purpose of circumcision, making it the correct choice.