**Core Concept**
Nonoxynol-9 is a non-ionic surfactant spermicide that disrupts the cell membrane of sperm, ultimately leading to their death. It is commonly used in contraceptive jellies, foams, and suppositories.

**Why the Correct Answer is Right**
Nonoxynol-9 works by creating pores in the sperm cell membrane, causing an influx of water and leading to cellular lysis. This mechanism is due to its surfactant properties, which allow it to interact with and disrupt the phospholipid bilayer of the sperm cell membrane. Nonoxynol-9 does not require the presence of enzymes or specific receptors to exert its effect.

**Why Each Wrong Option is Incorrect**
**Option A:** Nonoxynol-9 is not a form of hormonal contraception, as it does not affect hormone levels or bind to hormone receptors.
**Option B:** Nonoxynol-9 does not primarily work through the inhibition of prostaglandin synthesis, which is a mechanism associated with nonsteroidal anti-inflammatory drugs (NSAIDs).
**Option C:** Nonoxynol-9 is not a form of barrier contraception, as it does not physically prevent sperm from reaching the egg.

**Clinical Pearl / High-Yield Fact**
Nonoxynol-9 is often used in combination with other spermicides or barrier methods to enhance its contraceptive efficacy. However, its use should be limited to external applications, as it can cause vaginal irritation and other side effects if used excessively or for prolonged periods.

**Correct Answer:** C.