**Core Concept**
Leishmania is a genus of trypanosome parasites that cause leishmaniasis, a disease transmitted by sandflies. Culturing Leishmania requires a specific medium that supports its growth and replication.

**Why the Correct Answer is Right**
Leishmania is typically cultured in Novy-MacNeal-Nicolle (NNN) medium, a type of blood agar. This medium is enriched with rabbit or guinea pig blood, which provides the necessary nutrients for the parasite to grow. The NNN medium is also supplemented with antibiotics to prevent contamination. The parasite's growth is observed under a microscope, and the culture is maintained at a temperature range of 22-25°C.

**Why Each Wrong Option is Incorrect**
**Option A:** RPMI (Roswell Park Memorial Institute) medium is used for culturing various cell lines and some bacteria, but it is not suitable for Leishmania.
**Option B:** Sabouraud dextrose agar is a medium used for culturing fungi, not protozoa like Leishmania.
**Option C:** Luria-Bertani (LB) broth is a medium used for culturing bacteria, particularly E. coli, but it is not suitable for Leishmania.

**Clinical Pearl / High-Yield Fact**
Leishmania can be cultured in NNN medium, but it requires aseptic technique and a biohazard containment facility to prevent exposure to the parasite.

**Correct Answer: C. NNN medium.**