**Core Concept**
Kala-azar, also known as visceral leishmaniasis, is a severe form of leishmaniasis caused by the protozoan parasite *Leishmania donovani*. The treatment of kala-azar involves the use of antiprotozoal medications that target the parasite.

**Why the Correct Answer is Right**
Paromomycin is an aminoglycoside antibiotic that has been found to be effective in the treatment of kala-azar. It works by inhibiting protein synthesis in the parasite, ultimately leading to its death. Paromomycin is often used in combination with other medications, such as antimonials, to treat kala-azar.

**Why Each Wrong Option is Incorrect**
**Option A:** Diloxanide furoate is an anthelmintic medication used to treat amoebiasis, not kala-azar.
**Option B:** Metronidazole is an antibiotic and antiprotozoal medication used to treat a variety of infections, including giardiasis and amoebiasis, but it is not the primary treatment for kala-azar.
**Option D:** Spiramycin is a macrolide antibiotic used to treat various bacterial infections, but it is not effective against kala-azar.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the treatment of kala-azar often involves a combination of medications due to the development of resistance to single-drug regimens. Paromomycin is often used in combination with antimonials, such as sodium stibogluconate, to achieve optimal treatment outcomes.

**✓ Correct Answer: C. Paromomycin**