**Core Concept**
Kienbock disease is a rare bone disorder characterized by the avascular necrosis of a specific carpal bone in the wrist. This condition is caused by a disruption in the blood supply to the affected bone, leading to cell death and potential collapse of the bone structure.

**Why the Correct Answer is Right**
Kienbock disease specifically affects the lunate bone, which is one of the eight carpal bones in the wrist. The lunate bone receives its blood supply primarily from the anterior and posterior interosseous arteries, which can be compromised in certain situations, such as repetitive trauma or increased pressure on the bone. This compromise leads to ischemia and subsequent necrosis of the bone tissue.

**Why Each Wrong Option is Incorrect**
**Option A:**
* This option is incorrect because Kienbock disease specifically affects the lunate bone, not the scaphoid bone, which is also a carpal bone but involved in different pathologies.

**Option B:**
* This option is incorrect because Kienbock disease is a unique condition and not a general term for avascular necrosis of any bone, including the femoral head.

**Option C:**
* This option is incorrect because Kienbock disease is a distinct condition affecting the lunate bone, not the capitate bone, which is another carpal bone involved in different pathologies.

**Clinical Pearl / High-Yield Fact**
Kienbock disease is often associated with repetitive trauma or increased pressure on the lunate bone, which can be due to various factors such as scapholunate dissociation, ulnar variance, or repetitive wrist motion.

**Correct Answer: C. The lunate bone.**