In which one of the following pairs of diseases both are caused by viruses?

Options

A. Tetanus and typhoid
B. Whooping cough and sleeping sickness
C. Syphilis and AIDS
D. Measles and rabies

Explanation

To determine which pair of diseases are both caused by viruses, we can analyze each pair of diseases provided in the question.

### Step-by-Step Solution:

1. **Identify the first pair: Tetanus and Typhoid**
- Tetanus is caused by the bacterium *Clostridium tetani*.
- Typhoid is caused by the bacterium *Salmonella typhi*.
- **Conclusion**: Both diseases are bacterial. This pair is not the answer.

2. **Identify the second pair: Whooping Cough and Sleeping Sickness**
- Whooping cough is caused by the bacterium *Bordetella pertussis*.
- Sleeping sickness is caused by the protozoan *Trypanosoma gambiense*.
- **Conclusion**: This pair consists of a bacterial disease and a protozoan disease. This pair is not the answer.

3. **Identify the third pair: Syphilis and AIDS**
- Syphilis is caused by the bacterium *Treponema pallidum*.
- AIDS is caused by the virus *HIV* (Human Immunodeficiency Virus).
- **Conclusion**: This pair consists of a bacterial disease and a viral disease. This pair is not the answer.

4. **Identify the fourth pair: Measles and Rabies**
- Measles is caused by the virus *Paramyxovirus*.
- Rabies is caused by the virus *Rabies virus*.
- **Conclusion**: Both diseases are viral. This pair is the correct answer.

### Final Answer:
The correct pair of diseases that are both caused by viruses is **Measles and Rabies**.

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