Which of the following describes the function of a disinfectant?

The function of a disinfectant is primarily to kill or reduce pathogens on surfaces. Disinfectants are chemical agents designed for use on inanimate objects to eliminate or significantly lower the numbers of harmful microorganisms, particularly pathogens that can cause infection. This makes them essential in various settings, such as healthcare facilities and laboratories, where maintaining a clean environment is vital to prevent the spread of disease.

While the other options mention various aspects of microbial control, they do not accurately describe the specific role of disinfectants. For example, rendering a surface free of all living microorganisms refers more to sterilization, which is a more rigorous process than disinfection. Preserving biological samples is more related to additives that prevent deterioration rather than disinfection. Sterilizing surgical instruments indicates a complete destruction of all microbial life, which also exceeds the definition of disinfection. Therefore, the main focus of a disinfectant is its ability to mitigate harmful microorganisms, making the choice of killing or reducing pathogens on surfaces the most fitting description.