Final answer:
Hand washing is the single most effective means of controlling the spread of infectious organisms due to its ability to remove pathogens from the skin, thus preventing disease transmission.
Step-by-step explanation:
The student asks about the single most effective means of controlling the spread of infectious organisms. The correct answer is c. Hand washing. Hand washing is pivotal because it physically removes pathogens from the skin through friction and the action of soap and warm water. This can significantly reduce the transmission of diseases that are spread not only by direct contact but also through indirect contact, such as touching contaminated surfaces or the faecal-oral route. Additionally, hand washing can diminish the spread of respiratory illnesses by removing viruses from the hands before they can be transferred to the mouth, nose, or eyes. Therefore, proper hand washing technique is an essential practice in health management and crucial for preventing disease.