**Question:** Chemical used in vaginal sponge is

A. estrogen
B. progesterone
C. spermicide
D. lidocaine

**Core Concept:** Vaginal sponges are non-hormonal contraceptives used to prevent pregnancy. They contain chemicals that neutralize the sperm, rendering it unable to fertilize the egg.

**Why the Correct Answer is Right:** The correct answer is C. Spermicide, which is a chemical compound, is used in vaginal sponges to neutralize the male reproductive fluid, specifically, the sperm. This prevents fertilization and reduces the chances of pregnancy.

**Why Each Wrong Option is Incorrect:**

A. Estrogen and progesterone are hormones used in oral contraceptives, not vaginal sponges. Estrogen and progesterone are not neutralizing agents and do not prevent pregnancy.
B. Progesterone is a hormone involved in pregnancy maintenance and is not used for contraception. It is not a component of vaginal sponges.
D. Lidocaine is an anesthetic drug used for pain relief, not contraception. It does not have a role in preventing pregnancy.

**Clinical Pearl:** Vaginal sponges provide an alternative method for contraception, especially for women who cannot or choose not to use hormonal methods. They require proper application and regular replacement to maintain effectiveness.

**Correct Answer:** C. Spermicide (spermicidal agents, typically nonoxynol-9) is the chemical component used in vaginal sponges to prevent pregnancy by neutralizing sperm.