**Core Concept**
Rhinosporodiosis is a chronic, granulomatous infection caused by Rhinosporidium seeberi, a protist that affects the mucous membranes, particularly the nasal mucosa, conjunctiva, and skin. The condition is characterized by the formation of polypoid masses containing sporangia.

**Why the Correct Answer is Right**
The most common presentation of adult rhinosporodiosis is a nasal mass or polyp, which can cause nasal obstruction, epistaxis, and nasal discharge. The infection typically affects the nasal mucosa, leading to the formation of a polypoid mass that can be pedunculated or sessile. The sporangia within the polyp can rupture, releasing endospores that can cause further inflammation and tissue destruction.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because rhinosporodiosis can affect other mucous membranes, such as the conjunctiva and skin, but the nasal mucosa is the most common site of infection.
**Option B:** This option is incorrect because while the condition can cause nasal discharge and epistaxis, it is not the most common presentation.
**Option C:** This option is incorrect because rhinosporodiosis is not typically characterized by a single, large cystic lesion.

**Clinical Pearl / High-Yield Fact**
Rhinosporodiosis is a rare but distinctive condition that should be considered in the differential diagnosis of nasal masses, particularly in individuals with a history of exposure to contaminated water.

**Correct Answer:** C. A nasal mass or polyp.