Which of the following diseases is caused by bacilli?

The choice of tuberculosis is correct because it is specifically caused by the bacterium Mycobacterium tuberculosis, which is classified as a bacillus. Bacilli are rod-shaped bacteria, and Mycobacterium tuberculosis fits this classification perfectly. Tuberculosis primarily affects the lungs but can impact other areas of the body as well. The transmission of this disease occurs through the air when an infected person coughs or sneezes, releasing droplets that contain the bacterium.

On the other hand, syphilis is caused by Treponema pallidum, a spiral-shaped bacterium known as a spirochete. Influenza is caused by the influenza virus, which is a completely different type of pathogen (a virus, not a bacterium). Athlete's foot is a fungal infection caused by dermatophytes, which are types of fungi and not bacteria. Therefore, tuberculosis stands out as the disease caused specifically by bacilli among the options given.