During which stage of sleep, also known as delta sleep, would a person have slow breathing and be difficult to wake. A.
between stages 1 and 2 of non–rapid-eye-movement sleep
B.
in stage 4 of non–rapid-eye-movement sleep
C.
near the end of stage 3 of rapid-eye-movement sleep
D.
in stage 3 of non–rapid-eye-movement sleep

It's D. in stage 3 of non-rapid-eye-movement sleep

Explanation:

**PLATO**  "NREM-3 is when a person is in deep sleep and it lasts about 30 minutes. The person experiences slow breathing and pulse rates and limp muscles, and is difficult to wake. This stage is sometimes called delta sleep, because the brain produces slow delta waves."

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