**Core Concept**
The inguinal canal is a narrow, fibromuscular tube through which the spermatic cord passes in males and the round ligament of the uterus passes in females. It is a significant anatomical structure that allows for the passage of vital structures between the abdominal cavity and the external genitalia.

**Why the Correct Answer is Right**
The inferior epigastric artery is not a content of the inguinal canal because it arises from the external iliac artery and passes through the abdominal wall to supply the anterior abdominal wall muscles. In contrast, the spermatic cord in males and the round ligament of the uterus in females, along with the ilioinguinal nerve and the genital branch of the genitofemoral nerve, pass through the inguinal canal. The inguinal canal is a specific passageway for these structures, and the inferior epigastric artery does not traverse this canal.

**Why Each Wrong Option is Incorrect**
**Option A:** The spermatic cord is a content of the inguinal canal, containing the vas deferens, testicular arteries, and pampiniform plexus.
**Option B:** The ilioinguinal nerve passes through the inguinal canal and provides sensory innervation to the skin of the upper medial thigh and the root of the penis or upper part of the labia majora.
**Option C:** The genital branch of the genitofemoral nerve, also known as the internal spermatic nerve, enters the inguinal canal and provides motor innervation to the cremaster muscle.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the spermatic cord in males and the round ligament of the uterus in females are the primary contents of the inguinal canal. The ilioinguinal nerve and the genital branch of the genitofemoral nerve also pass through the canal, while the inferior epigastric artery does not.

**✓ Correct Answer: D. Inferior epigastric artery**