Final answer:
A surface free from dirt, oil, and microbes is most accurately described as being sterilized, though it may also be referred to as sanitized or disinfected depending on the method and level of microbial control achieved.
Step-by-step explanation:
If a surface is free from dirt, oil and/or microbes, it has been sanitized, disinfected, or sterilized depending on the degree of cleaning done. Cleaning simply removes visible dirt and is not necessarily related to microbes at all. Sanitization lowers the number of microbes present to a safe level, as defined by public health standards. To be considered sanitized, the item doesn't need to be free of all microbes but just reduced to a safe level. For example, dishes in a commercial dishwasher are sanitized using high temperatures that kill most microbes.
Disinfection inactivates most microbes but does not necessarily achieve the total removal of all potential pathogens. Items are treated with chemical disinfectants or heat to a level that is generally not safe for human tissue. On the other hand, sterilization is the highest level of microbial control, aiming to remove or kill all vegetative cells, endospores, and viruses. This can be done with physical means such as heat or chemical sterilants. Sterilization is typically required for items that come into contact with sterile tissues or are used in invasive procedures.