Which one of the following causes kala-azar?

Options

A. Ascaris
B. Trypanosoma
C. Leishmania
D. Bacteria

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism causes the disease known as Kala-azar.

2. **Analyzing the Options**: The options provided include:
- Ascaris
- Trypanosoma
- Leishmania
- Bacteria (general)

3. **Identifying the Organisms**:
- **Ascaris**: This is a type of roundworm that causes Ascariasis, which is an intestinal infection.
- **Trypanosoma**: This protozoan is responsible for sleeping sickness.
- **Leishmania**: This is a protozoan that is known to cause Kala-azar.
- **Bacteria**: Various bacteria can cause different diseases, but they are not responsible for Kala-azar.

4. **Determining the Correct Answer**: Since Leishmania is specifically known to cause Kala-azar, we can conclude that the correct answer is **Leishmania**.

5. **Final Answer**: The organism that causes Kala-azar is **Leishmania** (Option C).

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