Step 1: Hip dislocations are most often posterior, occasionally anterior, and sometimes central through the acetabulum.
Step 2: In a posterior dislocation, the hip is held flexed, adducted and internally rotated, and the limb appears shortened.
Step 3: This contrasts with an anterior dislocation, where the hip is flexed, abducted and externally rotated. The opposite rotation and abduction help distinguish the two.
Step 4: The combination of flexion, adduction and internal rotation matches option b.