**Core Concept**
Amphotericin-B is an antifungal medication used to treat systemic fungal infections. It belongs to the polyene class of antifungals, which work by binding to the fungal cell membrane and causing cell lysis.

**Why the Correct Answer is Right**
Amphotericin-B is obtained from the fungus *Streptomyces nodosus*. The fungus produces amphotericin-B as a secondary metabolite, which is extracted and purified for medical use. The polyene molecule binds to ergosterol in the fungal cell membrane, disrupting membrane integrity and ultimately causing cell death.

**Why Each Wrong Option is Incorrect**
**Option A:** This is not a known source of amphotericin-B.
**Option B:** This option is incorrect, as amphotericin-B is not derived from this fungus.
**Option D:** This option is also incorrect, as there is no known association between this fungus and the production of amphotericin-B.

**Clinical Pearl / High-Yield Fact**
Amphotericin-B is often used in combination with other antifungals to treat systemic fungal infections, such as candidemia and aspergillosis. It is also used to treat cryptococcal meningitis in HIV/AIDS patients.

**Correct Answer: C. *Streptomyces nodosus***