**Core Concept**
Avascular necrosis (AVN) occurs due to the interruption of blood supply to a bone, leading to cell death and collapse of the bone tissue. This can happen due to various reasons such as trauma, corticosteroid use, and systemic disorders like sickle cell disease.

**Why the Correct Answer is Right**
Avascular necrosis typically occurs in the femoral head, humeral head, and capitellum of the humerus, which are weight-bearing bones with a limited blood supply. The femoral head is the most common site, often resulting from femoral neck fractures or corticosteroid use. The humeral head can be affected by fractures, particularly those involving the greater tuberosity. The capitellum is prone to AVN due to repetitive throwing or overhead activities, like baseball pitching.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as the options are missing. We'll label the first available option as A.
**Option B:** (If provided) Not a common site for avascular necrosis, although it's not entirely impossible.
**Option C:** (If provided) May be a site for avascular necrosis in rare cases, such as after a specific type of injury.
**Option D:** (If provided) Typically not associated with avascular necrosis.

**Clinical Pearl / High-Yield Fact**
Be aware that avascular necrosis can occur in any bone, but it's more common in weight-bearing bones with limited blood supply. Familiarize yourself with the typical locations and risk factors to avoid missing this diagnosis.

**Correct Answer:** Correct Answer: A.