One of the following is caused by virus

Options

A. cholera
B. malaria
C. influenza
D. leprosy

Answer

To determine which of the listed diseases is caused by a virus, we can analyze each option provided:

1. **Cholera**: This disease is caused by the bacterium *Vibrio cholerae*. Therefore, cholera is a bacterial disease, not viral.

2. **Malaria**: Malaria is caused by the protozoan parasite *Plasmodium*. It is classified as a protozoal disease, not a viral one.

3. **Influenza**: Influenza, commonly known as the flu, is caused by the influenza virus. This is a viral disease.

4. **Leprosy**: Leprosy is caused by the bacterium *Mycobacterium leprae*. Thus, leprosy is also a bacterial disease.

From the analysis above, the only disease caused by a virus is **Influenza**.

### Final Answer:
The disease caused by a virus is **Influenza**.