**Core Concept**
The clinical presentation suggests a condition affecting the hip in a pediatric patient, with symptoms of pain and limited mobility. The **abrupt onset of pain** and **raised ESR** point towards an inflammatory or infectious process.

**Why the Correct Answer is Right**
Given the abrupt onset of hip pain in a child with a raised ESR and normal hemogram, the most likely diagnosis is **transient synovitis** or **septic arthritis**. The next line of management would involve distinguishing between these two conditions, often through imaging and possibly arthrocentesis to examine the synovial fluid for infection or inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:** Without more context, it's hard to assess, but typically, management wouldn't start here without further diagnostic clarification.
**Option B:** Similarly, this might not be the immediate step without knowing the specifics of the case.
**Option D:** This could be part of the management but not typically the first step without diagnostic confirmation.

**Clinical Pearl / High-Yield Fact**
In pediatric patients presenting with acute hip pain, it's crucial to consider **septic arthritis** due to its potential for rapid joint destruction and the need for urgent antibiotic treatment.

**Correct Answer:** D. Urgent ultrasound-guided aspiration of the hip.