**Core Concept**
Antrochoanal polyps are benign, inflammatory growths originating from the mucous membranes of the maxillary antrum and extending into the choana. They are characterized by a single stalk and a broad base, often causing nasal obstruction and postnasal drip.

**Why the Correct Answer is Right**
The treatment of choice for antrochoanal polyps is surgical removal, specifically endoscopic sinus surgery (ESS). This involves the use of a nasal endoscope to visualize the polyp and remove it with specialized instruments. The procedure is minimally invasive and allows for the preservation of surrounding tissue and function. The broad base of the polyp is often left intact to prevent recurrence.

**Why Each Wrong Option is Incorrect**
**Option A:** Antibiotics are not the primary treatment for antrochoanal polyps, as they are not caused by a bacterial infection. While antibiotics may be used to manage secondary infections, they do not address the underlying polyp tissue.

**Option B:** Nasal steroids may help reduce inflammation and swelling associated with antrochoanal polyps, but they do not provide a definitive treatment for the polyp itself. Steroids may be used as an adjunctive therapy to manage symptoms, but they are not a substitute for surgical removal.

**Option C:** Functional endoscopic sinus surgery (FESS) is a more extensive procedure than ESS, often used to treat chronic sinusitis or other complex sinus conditions. While FESS can be used to remove antrochoanal polyps, ESS is a more appropriate and less invasive option for this specific condition.

**Clinical Pearl / High-Yield Fact**
Antrochoanal polyps are often associated with a genetic predisposition, particularly in individuals with cystic fibrosis or other conditions affecting mucociliary clearance.

**Correct Answer:** C.