Which among the following STDs is caused by a protozoan?

Options

A. Syphilis
B. Gonorrhoea
C. Chlamydiasis
D. Trichomoniasis

Explanation

To determine which among the following STDs is caused by a protozoan, we will analyze the options provided:

1. **Identify the options**: The options given are:
- A) Syphilis
- B) Gonorrhea
- C) Chlamydiasis
- D) Trichomoniasis

2. **Classify the STDs**:
- **Syphilis**: This is caused by the bacterium *Treponema pallidum*, which is a type of bacteria.
- **Gonorrhea**: This is caused by the bacterium *Neisseria gonorrhoeae*, also a bacterial infection.
- **Chlamydiasis**: This is caused by the bacterium *Chlamydia trachomatis*, which is another bacterial STD.

3. **Identify the protozoan STD**:
- **Trichomoniasis**: This is caused by a protozoan parasite known as *Trichomonas vaginalis*. This makes it distinct from the other options, which are all bacterial infections.

4. **Conclusion**: Based on the analysis, the only STD among the options that is caused by a protozoan is **Trichomoniasis**.

Thus, the answer is **D) Trichomoniasis**.