**Core Concept**
The inguinal canal is a narrow passageway in the anterior abdominal wall that allows for the passage of structures between the abdominal cavity and the external genitalia. It is a critical anatomical structure that contains various contents, including blood vessels, nerves, and lymphatic vessels.

**Why the Correct Answer is Right**
The contents of the inguinal canal include the spermatic cord in males and the round ligament of the uterus in females. The spermatic cord contains the vas deferens, testicular arteries, and pampiniform plexus of veins, among other structures. In females, the round ligament of the uterus, a fibromuscular cord, passes through the inguinal canal.

**Why Each Wrong Option is Incorrect**
* **Option A:** The ilioinguinal nerve is indeed a content of the inguinal canal. It is a sensory nerve that provides innervation to the skin of the upper medial thigh and the root of the penis in males and the mons pubis and labia majora in females.
* **Option B:** The lymphatic vessels are also a content of the inguinal canal. They play a crucial role in draining lymph from the lower limb and external genitalia.
* **Option D:** The femoral artery is not a content of the inguinal canal. Instead, it is a major artery that lies in the femoral sheath, which is located lateral to the inguinal canal.

**Clinical Pearl / High-Yield Fact**
The inguinal canal is a common site for hernias, particularly indirect inguinal hernias, which occur when tissue, such as part of the intestine, protrudes through a weakness in the abdominal wall.

**Correct Answer: D. The femoral artery is not a content of the inguinal canal.**