Which of the Following Statements Is True of Progressive Cycles

Which of the following statements is true of progressive cycles during sleep?

A) With each progressive cycle, the non-REM periods are longer and the REM periods shorter.
B) Non-REM sleep lasts for only about 8-10 minutes, and REM sleep lasts for 90 minutes.
C) Non-REM sleep involves active dreaming, and REM sleep involves deep, unconscious sleep.
D) With each progressive cycle, the non-REM periods are shorter and the REM periods longer.