## Core Concept
Pertussis, also known as whooping cough, is a highly contagious respiratory illness caused by *Bordetella pertussis*. It is characterized by a distinctive cough and is often discussed in the context of vaccine-preventable diseases. The clinical features and complications of pertussis are crucial for diagnosis and management.

## Why the Correct Answer is Right
The correct answer, option , is associated with a feature not typical of pertussis. To accurately explain this, let's examine each option in the context of pertussis symptoms and characteristics.

## Why Each Wrong Option is Incorrect
- **Option A:** Typically, a feature of pertussis.
- **Option B:** Usually seen in pertussis.
- **Option C:** Commonly associated with pertussis.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the classic triad of pertussis includes a **paroxysmal cough**, a **post-tussive gag or vomiting**, and the characteristic **whoop**. However, not all patients exhibit the whoop, making diagnosis challenging.

## Correct Answer: D.