**Core Concept**
Sinusitis is an inflammation of the paranasal sinuses, typically caused by infection or obstruction. The major symptoms arise from increased pressure, mucus accumulation, and inflammation in the sinus cavities, affecting nasal airflow and facial structures.

**Why the Correct Answer is Right**
Halitosis (bad breath) is not a hallmark or direct symptom of sinusitis. While chronic or severe sinusitis may lead to secondary oral or dental issues, halitosis is not a primary or consistently reported symptom. In contrast, nasal blockage, facial congestion, and nasal congestion are directly linked to sinus inflammation and mucus buildup, all stemming from obstructed sinus drainage and inflammation of the mucosal lining.

**Why Each Wrong Option is Incorrect**
Option A: Nasal blockage is a classic symptom of sinusitis due to swollen mucous membranes and mucus plug formation.
Option B: Facial congestion results from pressure buildup in the sinuses, especially in the forehead, cheeks, and upper jaw.
Option C: Nasal congestion occurs due to inflammation and swelling of the nasal mucosa, blocking airflow.

**Clinical Pearl / High-Yield Fact**
In acute or chronic sinusitis, patients commonly present with unilateral or bilateral facial pain, nasal discharge, and reduced sense of smell. Always assess for nasal obstruction and facial pressure—halitosis should be evaluated for dental or oral causes, not as a primary sinusitis symptom.

✓ Correct Answer: D. Halitosis