Pei is an operating room nurse in charge of preparing the sterile field. Once she has prepared the sterile field, which of the following is acceptable for Pei
to do in order to protect it?

A. Pei bends down to pick up an instrument that fell on the floor,
removes the instrument from the operating room, and returns to
the sterile field.
B. Pei leans against the wall of the operating room in order to take a
break, and then she returns to the sterile field.
C. Pei leaves the operating room until the procedure begins to keep
any remaining pathogens on her from contaminating the sterile
field.
D. Pei stays in the operating room before the procedure begins to
ensure the sterile field is not left unattended.