Which of the following methods can be used to ensure that an experiment testing the effect of antibiotics on bacteria has not been contaminated?

The correct answer is D. All of the above. Contamination can significantly impact the accuracy and reliability of an experiment, and it is important to take steps to prevent it. Wearing gloves and a lab coat can help to prevent the transfer of contaminants from the hands and clothing of the experimenter to the experiment. Aseptic techniques involve taking steps to prevent contamination of the experiment by microorganisms. This can include using sterile equipment and supplies, working in a clean environment, and using disinfectants to kill or remove contaminants. Sterilized equipment and supplies have been treated to kill or remove all microorganisms, and using them can help to prevent contamination of the experiment.