Final answer:
The tables part of the sterile field should be placed at least 18 inches away from the walls. This distance is to prevent contamination and allow proper movement around the sterile field. The correct option is 3) 18.
Step-by-step explanation:
The question pertains to the guidelines for setting up a sterile field, which is a crucial aspect of ensuring aseptic technique in a medical environment. The correct distance for placing all tables as part of the sterile field from the walls is at least 18 inches.
This distance is recommended to maintain the sterility of the field by preventing contamination from the walls and ensuring that there's adequate space for healthcare providers to move around the field without risking breach of sterility.