**Core Concept**
Naegleria fowleri is a thermophilic, free-living amoeba that causes primary amebic meningoencephalitis (PAM). It is typically found in warm freshwater environments and can infect humans through the nasal route. A selective medium is necessary to isolate and culture this amoeba.

**Why the Correct Answer is Right**
The correct selective medium for Naegleria fowleri is non-nutrient agar (NNA) with grass sap as an enrichment source. NNA provides a solid surface for the amoeba to grow, while the grass sap serves as a nutrient source that promotes the growth of Naegleria fowleri. The addition of grass sap to NNA creates an environment that favors the growth of this thermophilic amoeba. This selective medium is essential for isolating and culturing Naegleria fowleri in the laboratory.

**Why Each Wrong Option is Incorrect**
**Option A:** Blood agar is not a suitable medium for Naegleria fowleri as it does not provide the necessary nutrients for its growth. Blood agar is typically used for culturing bacteria, not amoebas.

**Option B:** Sabouraud agar is a medium used for culturing fungi, not amoebas. It does not provide the necessary nutrients for the growth of Naegleria fowleri.

**Option C:** Buffered charcoal yeast extract (BCYE) agar is a selective medium used for culturing Legionella bacteria, not Naegleria fowleri.

**Clinical Pearl / High-Yield Fact**
Naegleria fowleri can cause a rapidly progressive and often fatal disease, PAM, which has a mortality rate of nearly 100% if left untreated. Early diagnosis and treatment with antiparasitic medications are crucial for survival.

**Correct Answer:** C. Non-nutrient agar with grass sap.