Option 1: Tuberculosis is not caused by a virus. It is caused by the bacteria Mycobacterium tuberculosis.
Option 2: Typhoid is not caused by a virus. It is caused by the bacteria Salmonella typhi.
Option 3: Influenza is caused by a virus. Influenza viruses, specifically types A, B, and C, are responsible for causing the flu.
Option 4: Diphtheria is not caused by a virus. It is caused by the bacterium Corynebacterium diphtheriae.
Therefore, the correct answer is option 3 - Influenza, as it is the only disease in the given list that is caused by a virus. It is important to note that viruses are responsible for causing numerous diseases, including common cold, measles, mumps, chickenpox, HIV/AIDS, and many others.