## **Core Concept**
The question pertains to the treatment of *Bordetella pertussis* infection, commonly known as whooping cough. The management of pertussis involves the use of antibiotics to reduce the severity and duration of symptoms, as well as to prevent transmission.

## **Why the Correct Answer is Right**
The correct answer, **C. Azithromycin**, is a macrolide antibiotic that is effective against *Bordetella pertussis*. Macrolides, including azithromycin, clarithromycin, and erythromycin, are the first-line treatments for pertussis. Azithromycin is preferred, especially in children, due to its favorable side effect profile, once-daily dosing, and shorter treatment course (typically 5 days).

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and cannot be evaluated.
- **Option B:** This option is blank and cannot be evaluated.
- **Option D:** This option is blank and cannot be evaluated.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that macrolide antibiotics (e.g., azithromycin) are the treatment of choice for pertussis, particularly in the early stage of the disease. They are most effective in reducing the contagious period and alleviating symptoms when started early.

## **Correct Answer:** C. Azithromycin