This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2019, Subject name: Physiology
Waves seen in EEG during stage 4- NREM period of sleep is: 
Select and explain. 
A. Alpha, B. Beta, C. Delta, D. Theta
C: Delta
Answer: C: Delta 
Explanation: - REM sleep shows - b waves - so, called as paradoxical sleep. (because even though the person is asleep, the waves of ale wakefulness-b waves are recorded)- NREM sleep - 4 stages* Stage I - Superficial stage - eyes closed & person is in sleep latency - a waves are seen* Stage II - Sleep spindles & large K - complexes are seen * Stage III - Theta waves are seen. * Stage IV - Deeper stages of sleep - delta waves are seen