What Is a Typical REM and N-REM Cycling in Humans

Multiple Choice

What is a typical REM and N-REM cycling in humans?

A) First half of sleep: N-REM dominates;second half of sleep: REM dominates.
B) First half of sleep: REM dominates;second half of sleep: N-REM dominates.
C) First half of sleep: only N-REM occurs;second half of sleep: only REM occurs.
D) First half of sleep: only REM occurs;second half of sleep: only N-REM occurs.