**Core Concept**
The innervation of the external genitalia is crucial for sexual function and sensation. The pudendal nerve, a branch of the sacral plexus, is responsible for the sensory and motor innervation of the glans penis, among other structures.

**Why the Correct Answer is Right**
The pudendal nerve arises from the S2-S4 nerve roots and provides sensory innervation to the glans penis, as well as motor innervation to the external urethral sphincter and other muscles of the perineum. This nerve is essential for maintaining normal sexual function and preventing conditions such as erectile dysfunction. The pudendal nerve is also responsible for transmitting sensory information from the glans penis, including pain, temperature, and touch.

**Why Each Wrong Option is Incorrect**
**Option A:** The genital branch of the genitofemoral nerve primarily supplies the cremaster muscle and the skin of the anterior superior aspect of the pubis, not the glans penis.

**Option B:** The ilioinguinal nerve provides sensory innervation to the skin of the medial thigh, the root of the penis, and the upper medial aspect of the scrotum, but not the glans penis.

**Option C:** The iliohypogastric nerve supplies the skin of the lower abdominal wall and the hip, but not the glans penis.

**Clinical Pearl / High-Yield Fact**
The pudendal nerve is also responsible for innervating the anal sphincter, making it a critical nerve for maintaining continence.

**Correct Answer:**
✓ Correct Answer: D. Pudendal nerve