Jake, a Float Nurse on a Surgical Unit Is Covering

Jake, a float nurse on a surgical unit is covering for another nurse Dianne while she is off the floor on her lunch break. Jake administers a dose of a controlled substance to one of Dianne's clients for pain and documents it on the MAR. He reports this to her when she returns from lunch, and she exclaims, "Oh no, I gave him a dose before I left for break, I must have forgotten to sign for it." What was the main factor that led to this error?

A) Poor communication between the two nurses
B) Not checking for documentation on the controlled substance sheet
C) No documentation on the MAR
D) Relief nurse should not be administering medications