**Core Concept**
Avascular necrosis (AVN) of the femoral head is a condition characterized by the loss of blood supply to the bone tissue, leading to cell death and potential collapse of the femoral head. This condition often results from a disruption in the blood supply to the femoral head, which can be caused by various factors such as trauma, steroid use, or certain medical conditions.

**Why the Correct Answer is Right**
AVN is commonly seen in the subcapital region of the femur, which is the area just below the femoral neck. This region is particularly susceptible to AVN due to its blood supply, which is primarily provided by the medial retinacular and lateral retinacular branches of the medial and lateral circumflex femoral arteries. When these arteries are compromised, the blood supply to the subcapital region is disrupted, leading to AVN.

**Why Each Wrong Option is Incorrect**
* **Option A:** Intertrochanteric fractures typically involve the region between the greater and lesser trochanters of the femur. While AVN can occur in this region, it is less common than subcapital AVN.
* **Option C:** Transcervical fractures involve the neck of the femur but are more proximal than subcapital fractures. AVN can occur in this region, but it is not as common as subcapital AVN.
* **Option D:** Basal fractures involve the distal end of the femur, near the knee joint. AVN is not typically associated with basal fractures.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that AVN can occur in any region of the femur, but the subcapital region is the most common site due to its blood supply. A thorough understanding of the blood supply to the femur is crucial in diagnosing and managing AVN.

**Correct Answer:** B. Subcapital