This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Specific θ waves are seen in 
Select and explain. 
A. NREM 1, B. NREM 2, C. NREM 3, D. REM
D: REM
Answer: D: REM 
Explanation: θ waves are seen in both NREM 1 & REM.
But specific θ waves indicate hippocampal activity seen in REM phase of sleep.