**Core Concept**
The fourchette is a fibromuscular structure located in the perineum. It plays a crucial role in maintaining the perineal body's integrity and supporting the urogenital diaphragm. The fourchette is formed by the fusion of the two labia minora.

**Why the Correct Answer is Right**
The fourchette is a dense fibromuscular structure composed of the transverse perineal muscles and the superficial perineal connective tissue. It is situated at the posterior aspect of the vaginal opening and is closely associated with the perineal body. The fourchette serves as a critical attachment point for the vaginal epithelium and helps to maintain the perineal body's structural integrity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the fourchette is not formed by the bulbocavernosus muscle.
**Option B:** This option is incorrect because the fourchette is not formed by the superficial transverse perineal muscle alone.
**Option C:** This option is incorrect because the fourchette is not formed by the external anal sphincter muscle.

**Clinical Pearl / High-Yield Fact**
During vaginal delivery, the fourchette can be susceptible to injury, leading to the formation of a perineal tear. In such cases, prompt surgical repair is essential to prevent long-term complications and maintain perineal integrity.

**Correct Answer: C. The superficial transverse perineal muscle and the bulbocavernosus muscle.**