At First the Subject Had Difficulty Falling Asleep in the Sleep

Multiple Choice

At first the subject had difficulty falling asleep in the sleep lab, but finally drifted into sleep and was not awakened when a student researcher knocked a can of soda off of the desk. The EEG is displaying a slow regular pattern with occasional sleep spindles. The researchers feel confident that the subject is

A) about to wake up.
B) now in stage 2 of the sleep cycle.
C) dreaming.
D) in REM sleep.