Final answer:
In OR attire, the hairnet should be donned first to prevent contamination. This is followed by the mask, gown, and gloves, while shoe covers may come either earlier or later in the process.
Step-by-step explanation:
When changing into operating room (OR) attire, the item that must be donned first is typically the hairnet (A). The order of donning protective clothing is important in maintaining sterility and preventing contamination in the OR environment. Generally, the sequence is to start with items that secure hair and head coverings, followed by masks, to prevent the shedding of hair or dandruff onto the sterile gown or other sterile attire. After these items, the gown and gloves are donned in a sterile manner, ensuring the outside of the gown and gloves remain uncontaminated. Shoe covers are often put on either before entering the changing area or as one of the last items before entering the OR.