**Core Concept**
Acute appendicitis is a surgical emergency characterized by inflammation of the appendix, typically presenting with periumbilical pain that shifts to the right lower quadrant. Early diagnosis relies on clinical assessment, as imaging and laboratory tests are secondary and often less specific.

**Why the Correct Answer is Right**
Physical examination, particularly the presence of rebound tenderness, Rovsing’s sign, and McBurney’s point tenderness, is the cornerstone of diagnosing acute appendicitis. These signs reflect localized peritoneal irritation due to inflammation. While imaging (e.g., ultrasound or CT) can confirm the diagnosis, they are not first-line and are often used only when clinical suspicion is low or in atypical cases. The physical exam remains the most practical, accessible, and cost-effective initial tool in a typical outpatient or emergency setting.

**Why Each Wrong Option is Incorrect**
Option A: History alone is insufficient — while symptoms like anorexia, nausea, or fever are helpful, they are non-specific and often mimic other conditions.
Option C: X-ray abdomen is not sensitive for appendicitis — it may show bowel obstruction or free air but lacks specificity and is not a reliable screening tool.
Option D: Ba meal (barium meal) is outdated and not used in diagnosing acute appendicitis — it is a historical radiographic test with poor sensitivity and no role in current practice.

**Clinical Pearl / High-Yield Fact**
In the absence of imaging, clinical examination remains the gold standard. A positive McBurney’s point tenderness, especially with rebound tenderness, strongly suggests appendicitis and warrants urgent surgical evaluation.

✓ Correct Answer: B. Physical examination