In _____ sleep, the fetus may be observed to have infrequent or absent body movements, normal FHR baseline, minimal variability, and a nonreactive NST, but may respond to external stimuli. Such typically occurs by 28 to 32 weeks' gestation.
A. REM (active sleep state)
B. Non-REM (quiet sleep state)
a) REM (active sleep state)
b) Non-REM (quiet sleep state)
c) Deep sleep state
d) Light sleep state