Final answer:
Sterilization is the most effective contraceptive method, involving surgical procedures that are considered irreversible.
Step-by-step explanation:
The most effective contraceptive method is sterilization. In both sexes, sterilization generally involves surgical procedures that are considered irreversible. Additional surgery may be able to reverse a sterilization procedure, but there are no guarantees. Male sterilization is generally less invasive and less risky than female sterilization.