**Core Concept**
Sinusitis is a common inflammatory condition affecting the paranasal sinuses, often resulting from viral or bacterial infections, allergies, or anatomical abnormalities. The clinical presentation of sinusitis can vary, but it typically involves a combination of nasal and facial symptoms.

**Why the Correct Answer is Right**
Halitosis, or bad breath, is not typically considered a major symptom of sinusitis. While sinusitis can cause postnasal drip, which may contribute to halitosis, this is not a primary or distinctive symptom of the condition. In contrast, nasal congestion, facial pain or pressure, and nasal blockage are classic symptoms of sinusitis, resulting from the inflammation and swelling of the nasal passages and sinuses. The Eustachian tube dysfunction can also be associated with some cases of sinusitis.

**Why Each Wrong Option is Incorrect**
**Option A:** Nasal blockage is actually a major symptom of sinusitis, caused by the swelling of the nasal mucosa and turbinates.
**Option B:** Facial congestion, or facial pain and pressure, is a common symptom of sinusitis, resulting from the inflammation of the sinuses and surrounding tissues.
**Option C:** Nasal congestion is a hallmark symptom of sinusitis, caused by the increased mucus production and swelling of the nasal passages.

**Clinical Pearl / High-Yield Fact**
It's essential to note that while sinusitis can cause a range of symptoms, the presence of fever, facial pain or pressure, and nasal congestion should prompt a diagnosis of acute bacterial sinusitis.

**Correct Answer:**
✓ Correct Answer: D. Halitosis