Which of the following is STD?

Options

A. Cancer
B. Trichomoniasis
C. Pneumonia
D. malaria

Answer

To determine which of the following is a sexually transmitted disease (STD), we need to analyze each option provided:

1. **Cancer**:
- Cancer is not classified as an STD. It is a disease characterized by the uncontrolled growth of abnormal cells in the body. While some cancers can be associated with viral infections (like HPV), cancer itself is not transmitted through sexual contact.

2. **Trichomoniasis**:
- Trichomoniasis is indeed an STD. It is caused by the parasite Trichomonas vaginalis, which is transmitted through sexual contact with an infected person. This makes trichomoniasis the correct answer.

3. **Pneumonia**:
- Pneumonia is an infection that inflames the air sacs in one or both lungs and is caused by various pathogens, including bacteria and viruses. It is not transmitted sexually.

4. **Malaria**:
- Malaria is caused by the Plasmodium species and is transmitted through the bite of infected female Anopheles mosquitoes. It is not an STD.

Based on this analysis, the only option that qualifies as a sexually transmitted disease is **trichomoniasis**.

### Final Answer:
The STD among the options provided is **trichomoniasis**.