The causal organism for African sleeping sickness is

Options

A. T.gambiense
B. T.tangela
C. T.rhodesiense
D. Trypanosoma cruzi

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the causal organism of African sleeping sickness. This is a disease primarily affecting humans and is known for its severe neurological effects.

2. **Identifying the Options**: The options provided are:
- 1) Trypanosoma gambiense
- 2) Trypanosoma tangela
- 3) Trypanosoma rhodesiense
- 4) Trypanosoma cruzi

3. **Analyzing the Causal Organisms**:
- **Trypanosoma gambiense**: This is a protozoan parasite known to cause African sleeping sickness (also called Gambian sleeping sickness).
- **Trypanosoma rhodesiense**: This is another type of Trypanosoma that can also cause African sleeping sickness (known as Rhodesian sleeping sickness), but it is less common.
- **Trypanosoma tangela**: This is not a recognized species associated with African sleeping sickness.
- **Trypanosoma cruzi**: This organism is known for causing Chagas disease, not African sleeping sickness.

4. **Determining the Correct Answer**: Based on the information, both Trypanosoma gambiense and Trypanosoma rhodesiense can cause African sleeping sickness. However, Trypanosoma gambiense is the more prevalent cause in humans.

5. **Final Answer**: The correct answer is **Trypanosoma gambiense**.