Duke Is Exhausted and Plops Down on the Couch

Multiple Choice

Duke is exhausted and plops down on the couch.Fifteen minutes after falling asleep,Duke is not awakened by the refrigerator cycling on.He is,however,awakened by his roommate opening the refrigerator door.What type of brain waveforms did Duke display right before being awakened?

A) Delta waves
B) Theta waves
C) Beta waves
D) Theta waves with sleep spindles and K-complexes