**Core Concept**
Femoral fractures can be classified based on their location and displacement, leading to varying complications such as avascular necrosis (AVN). AVN occurs due to the interruption of blood supply to the bone, which can happen when the fracture disrupts the nutrient arteries that supply the femoral head.

**Why the Correct Answer is Right**
The correct answer is **C. Subcapital fracture**. Subcapital fractures occur just below the femoral neck and are a common cause of AVN. This is because the fracture disrupts the blood supply to the femoral head, which is primarily provided by the medial and lateral circumflex femoral arteries. The nutrient artery to the head of the femur also passes through the femoral neck, making subcapital fractures particularly prone to AVN. The risk of AVN is higher in subcapital fractures compared to other types of femoral fractures.

**Why Each Wrong Option is Incorrect**
**Option A:** Transcervicular fractures, also known as intracapsular fractures, can also cause AVN, but the risk is lower compared to subcapital fractures.

**Option B:** Extra-capsular fractures, which occur outside the joint capsule, have a lower risk of AVN compared to subcapital fractures.

**Option D:** Intertrochanteric fractures, which occur between the greater and lesser trochanters, have a lower risk of AVN compared to subcapital fractures.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the location and displacement of femoral fractures significantly influence the risk of complications such as AVN. A thorough understanding of fracture classification and the associated risks is crucial for making accurate diagnoses and developing effective treatment plans.

**Correct Answer:** C. Subcapital fracture