Which of the following is an STD

Options

A. Measles
B. Syphilis
C. Diphtheria
D. Cancer

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks to identify which of the given options is a Sexually Transmitted Disease (STD).

2. **Defining STD**: An STD is defined as a Sexually Transmitted Disease, which means it is a disease that is transmitted from one person to another through sexual contact.

3. **Analyzing the Options**:
- **Measles**: Caused by the measles virus, primarily affecting children and spread through respiratory droplets. This is not an STD.
- **Syphilis**: Caused by the bacterium *Treponema pallidum*, this disease is transmitted through sexual contact. This is an STD.
- **Diphtheria**: Caused by the bacterium *Corynebacterium diphtheriae*, it spreads through respiratory droplets and personal contact, but it is not classified as an STD.
- **Cancer**: Cancer is not a contagious disease and does not spread from person to person through sexual contact or otherwise.

4. **Identifying the Correct Answer**: Based on the analysis, the only option that qualifies as an STD is **Syphilis**.

5. **Conclusion**: Therefore, the answer to the question is **Syphilis**.