**Core Concept**
Rhinosporidiosis is a chronic, granulomatous infection caused by Rhinosporidium seeberi, a protist that primarily affects the mucous membranes of the nose, mouth, and conjunctiva. The disease is characterized by the formation of polyps or nodules, which are composed of aggregates of the infective spores.

**Why the Correct Answer is Right**
The most common presentation of adult rhinosporidiosis is a nasal polyp, which is usually painless and may cause nasal obstruction, epistaxis, or discharge. The polyp is composed of a mass of spores, surrounded by a fibrovascular stroma, and is often mistaken for a benign nasal polyp. The diagnosis of rhinosporidiosis is confirmed by histopathological examination of the tissue, which shows the presence of the characteristic spores.

**Why Each Wrong Option is Incorrect**
* **Option A:** While rhinosporidiosis can affect the conjunctiva, the most common presentation is not conjunctival involvement.
* **Option B:** Rhinosporidiosis is not typically characterized by a painful mass, so this option is incorrect.
* **Option D:** While rhinosporidiosis can cause a variety of symptoms, a skin lesion is not the most common presentation.

**Clinical Pearl / High-Yield Fact**
Rhinosporidiosis is often mistaken for a benign nasal polyp, so it's essential to include it in the differential diagnosis of nasal polyps, especially in patients with a history of trauma or exposure to contaminated water.

**Correct Answer:** C. Nasal polyp