**Core Concept**
Transient synovitis of the hip is a self-limiting inflammatory condition affecting the synovial membrane of the hip joint, commonly seen in children. It mimics septic arthritis but lacks systemic signs and does not involve joint destruction. The deformity observed is due to inflammation-induced joint swelling and soft tissue contractures.

**Why the Correct Answer is Right**
In transient synovitis, joint swelling leads to mechanical restrictions. Inflammation causes pain and stiffness, resulting in abnormal joint positioning. The joint may be in **abduction** (due to muscle guarding), **flexion** (from passive joint restriction), and **external rotation** (due to altered biomechanics and ligamentous tension). These postures are not fixed but represent functional deformities from pain and limited movement. Thus, all three deformities can be observed clinically.

**Why Each Wrong Option is Incorrect**
Option A: Abduction is not a typical or exclusive finding; it's a secondary consequence of pain and guarding, not a defining feature.
Option B: Flexion is a common posture due to joint stiffness, but it's not specific or isolated.
Option C: External rotation is a common finding, but it is not the only or primary deformity.

**Clinical Pearl / High-Yield Fact**
Transient synovitis presents with acute hip pain, limping, and limited range of motion, but no fever or systemic illness. It is often misdiagnosed as septic arthritis, so clinical correlation and joint aspiration are essential. The deformity is transient and resolves within days to weeks with rest and NSAIDs.

✓ Correct Answer: D. All of the above