expain Four units of packed RBCs were used in the operating room at 3 p.m. Can the remaining 2 units be returned to the blood bank at 5 p.m.? a. Yes, if the 2 units have been kept under the proper storage conditions b. Yes, but only if the units are to be used for the same patient c. No, units may have been out of blood bank for more than 4 hours d. No, units have been out of the blood bank for longer than 30 minutes