**Core Concept**
Abduction of the thigh is a complex movement that involves the coordination of multiple muscles and anatomical structures. The primary muscles responsible for thigh abduction are the gluteus medius and minimus, which originate from the ilium and insert into the greater trochanter of the femur. This movement is also influenced by the position of the hip joint and the surrounding soft tissues.

**Why the Correct Answer is Right**
Thigh abduction is limited by the position of the hip joint, particularly the angle between the femoral head and the acetabulum. As the hip joint approaches 90 degrees of abduction, the fascia lata and surrounding soft tissues, including the iliotibial tract, begin to restrict movement. Additionally, the gluteus medius and minimus muscles, which are responsible for stabilizing the hip in abduction, become fatigued and less effective as the movement continues.

**Why Each Wrong Option is Incorrect**
**Option A:** The tensor fasciae latae muscle, while contributing to thigh abduction, is not the primary limiting factor in this movement.
**Option B:** The piriformis muscle, which lies deep to the gluteus medius, is not directly involved in limiting thigh abduction.
**Option C:** The iliopsoas muscle, which is responsible for hip flexion, does not directly limit thigh abduction.

**Clinical Pearl / High-Yield Fact**
Remember that the gluteus medius and minimus muscles are responsible for stabilizing the hip in abduction, and their weakness or fatigue can lead to abnormal movement patterns and increased risk of injury.

**Correct Answer: D.**