**Core Concept:** Avascular Necrosis (AVN) of femoral head is a condition characterized by the death of bone cells due to lack of blood supply, leading to bone collapse and joint damage. It is often associated with risk factors and clinical presentations.

**Why the Correct Answer is Right:** AVN of femoral head is most common in the elderly population, specifically those over the age of 50. This age group is more prone to develop AVN due to degenerative changes in the hip joint, which can impair blood flow and lead to bone necrosis.

In this case, option C ("Elderly") is the correct answer because it addresses the age-related risk factor for developing AVN of the femoral head.

**Why Each Wrong Option is Incorrect:**

A. "Young Adults": While young adults can develop AVN, it is less common in this age group due to better bone health and blood flow.

B. "Infective Endocarditis": This is a separate clinical entity and not a risk factor for AVN of the femoral head.

D. "Osteonecrosis secondary to trauma": While trauma can cause AVN, it is not the most common cause and does not specifically address the age-related risk factor.

**Clinical Pearl / High-Yield Fact:** Osteonecrosis is a complex condition with multiple causes. Understanding the risk factors, such as age, is essential for its diagnosis and management. Knowledge of AVN in the elderly population can help to recognize the condition early and provide appropriate treatment to prevent further joint damage and improve outcomes.