**Core Concept**
Posterior dislocation of the hip occurs when the femoral head is displaced out of the acetabulum in a posterior direction, often due to a severe force applied to the flexed hip, such as in a motor vehicle accident or a fall from a height. This injury typically results in a shortened, externally rotated, and flexed position of the hip.

**Why the Correct Answer is Right**
The femoral head is displaced out of the acetabulum in a posterior direction, which means it is positioned behind the acetabulum. This displacement is often accompanied by a shortened and externally rotated position of the affected limb. The flexion of the hip is due to the force applied to the flexed hip, causing the femoral head to displace posteriorly. The shortened position is a result of the femoral head being displaced out of the acetabulum, which reduces the overall length of the affected limb.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the hip is not typically positioned in extension in a posterior dislocation of the hip.
* **Option B:** This option is incorrect because the hip is not typically positioned in abduction in a posterior dislocation of the hip.
* **Option C:** This option is incorrect because the hip is not typically positioned in internal rotation in a posterior dislocation of the hip.

**Clinical Pearl / High-Yield Fact**
A patient with a posterior dislocation of the hip may present with a shortened, externally rotated, and flexed position of the affected limb, often with a palpable femoral head posterior to the acetabulum.

**Correct Answer: C. Flexed, shortened, and externally rotated position of the hip.**