**Core Concept**
Sinusitis is a common inflammatory condition affecting the paranasal sinuses, often caused by viral or bacterial infections. The symptoms can range from mild to severe, depending on the extent of inflammation and infection. A minor symptom of sinusitis is often a subtle indicator of the underlying condition.

**Why the Correct Answer is Right**
The correct answer is related to the autonomic nervous system's response to inflammation. During sinusitis, the trigeminal nerve's ophthalmic branch is irritated, leading to parasympathetic stimulation of the lacrimal gland. This results in an increase in tear production, manifested as excessive tearing or a watery eye. This symptom is often mild and may not be immediately associated with sinusitis.

**Why Each Wrong Option is Incorrect**
**Option A:** Halitosis - While sinusitis can cause bad breath, it is not a minor symptom. Halitosis is more commonly associated with oral infections or digestive issues.
**Option B:** Ear pain - Ear pain can be a symptom of sinusitis due to the close proximity of the sinuses and the Eustachian tube. However, it is not typically considered a minor symptom.
**Option C:** Fatigue - Fatigue can be a symptom of many conditions, including sinusitis. However, it is a non-specific symptom and not a minor indicator of sinusitis.

**Clinical Pearl / High-Yield Fact**
The "3 Cs" of sinusitis are:
* Congestion
* Cough
* Corrugated nasal mucosa

When evaluating a patient with suspected sinusitis, these symptoms can help guide the diagnosis.

**Correct Answer: C. Excessive tearing.**