Which of the following is a method of direct transmission?

Direct transmission refers to the transfer of infectious agents through immediate physical contact between an infected individual and a susceptible host. This can occur through activities such as touching, coughing, sneezing, or any direct exposure to respiratory droplets.

Coughing on another person is a clear example of direct transmission, as it involves the expulsion of respiratory droplets that can contain pathogens directly into the air and onto someone else. This form of transmission is significant in the spreading of diseases, especially respiratory infections, since the droplets can land on the mucous membranes of the mouth, nose, or eyes of the other person.

In contrast, using contaminated tools involves indirect transmission, where pathogens are transferred from tools to a host without direct contact. Cleaning surfaces is also a method to prevent transmission rather than a means of transmitting pathogens itself. Handling waste products may be associated with risks but does not constitute direct transmission unless it involves direct contact with an infected individual. Therefore, coughing on another person distinctly fits the criteria for direct transmission.