**Core Concept**
Posterior dislocation of the hip occurs when the femoral head is displaced out of the acetabulum in a posterior direction. This type of dislocation is often associated with a flexed, adducted, and internally rotated position of the lower limb.

**Why the Correct Answer is Right**
In posterior dislocation of the hip, the femoral head is displaced posteriorly, resulting in a flexed, adducted, and internally rotated position of the lower limb. This occurs due to the strong posterior capsule of the hip joint, which resists external rotation and abduction. As a result, the lower limb assumes a characteristic position of adduction, internal rotation, and flexion. The sciatic nerve, which runs posteriorly to the hip joint, may be stretched or injured in this type of dislocation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because posterior dislocation of the hip is not typically associated with external rotation and abduction. In fact, the strong posterior capsule of the hip joint resists external rotation and abduction.
**Option C:** This option is incorrect because abduction, external rotation, and flexion are not characteristic of posterior dislocation of the hip. The lower limb typically assumes a position of adduction, internal rotation, and flexion.
**Option D:** This option is incorrect because while abduction and flexion may occur in some cases of hip dislocation, internal rotation and abduction are not characteristic of posterior dislocation of the hip.

**Clinical Pearl / High-Yield Fact**
In cases of posterior dislocation of the hip, it is essential to identify the characteristic position of the lower limb, which is adduction, internal rotation, and flexion. This can help guide further management and reduce the risk of complications.

**✓ Correct Answer: B. Adduction, internal rotation and flexion**