**Core Concept**
In acute appendicitis, certain signs are commonly observed, while others are less typical or not present at all. The clinical presentation of appendicitis can vary, but some classic signs are often absent or less prominent in acute appendicitis.

**Why the Correct Answer is Right**
The correct answer is **D**. In acute appendicitis, the following signs are typically not seen or are less common:
- **Option D:** Mass peritonitis or generalized peritonitis is not a characteristic finding in acute appendicitis, as it usually presents with localized peritonitis or rebound tenderness.

**Why Each Wrong Option is Incorrect**
- **Option A:** Not available.
- **Option B:** Not available.
- **Option C:** Not available.

**Clinical Pearl / High-Yield Fact**
In acute appendicitis, the McBurney's point sign (tenderness at the junction of the middle and outer third of the right lower quadrant) is often the most reliable indicator of appendicitis.

**Correct Answer:** D.