**Core Concept**
The pudendal block is a regional anesthesia technique used to anesthetize the perineal area, including the genitalia and anal regions. This block involves the blockade of the pudendal nerve, which arises from the S2-S4 nerve roots.

**Why the Correct Answer is Right**
The pudendal nerve is formed by the S2-S4 sacral nerve roots, specifically through the union of the ventral rami of these roots. The pudendal nerve carries sensory and motor fibers to the perineum, including the external genitalia and anal region. The blockade of the pudendal nerve results in the loss of sensation and motor function in the perineal area. This is achieved by injecting local anesthetic around the pudendal nerve as it exits the greater sciatic foramen.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the pudendal nerve does not arise from the L5-S1 nerve roots. The L5-S1 nerve roots contribute to the formation of the sciatic nerve, not the pudendal nerve.
* **Option B:** This option is incorrect because the obturator nerve arises from the L2-L4 nerve roots and provides motor innervation to the adductor muscles of the thigh. It does not contribute to the formation of the pudendal nerve.
* **Option C:** This option is incorrect because the femoral nerve arises from the L2-L4 nerve roots and provides motor innervation to the muscles of the anterior thigh. It does not contribute to the formation of the pudendal nerve.

**Clinical Pearl / High-Yield Fact**
The pudendal nerve block is commonly used in obstetrics and gynecology to provide anesthesia for vaginal deliveries and minor gynecological procedures.

**Correct Answer:** C. The pudendal nerve arises from the S2-S4 nerve roots.