What is the primary function of spermicidal foam?

Spermicidal foam is designed primarily to kill sperm, making it an effective form of birth control. The active ingredients in spermicidal foam are formulated to immobilize or destroy sperm before they can reach an egg, thus reducing the likelihood of fertilization.

Understanding the context of the other choices helps clarify why they do not apply to the primary function of spermicidal foam. For instance, while some contraceptive methods aim to prevent ovulation, spermicidal foam does not act on this physiological process. Increasing libido is also unrelated, as spermicidal foam does not have any effect on sexual desire. Lastly, while some formulations of spermicides may provide lubrication, this is not the primary function; the main goal remains the destruction of sperm to prevent pregnancy.