Rebecca Is Hooked Up to an Electroencephalograph (EEG)in a Sleep

Multiple Choice

Rebecca is hooked up to an electroencephalograph (EEG) in a sleep lab.As the researcher watches the printout from the EEG,delta waves appear.What can the researcher conclude about Rebecca's state of consciousness,based on this information

A)  She is currently in REM sleep. 
B)  She has just entered stage 1 sleep. 
C)  She has just entered stage 3 sleep. 
D)  She is still awake but is relaxed and drowsy.