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: Physiology
The frequency of beta waves (per sec) in EEG is 
Select and explain. 
A. 0-4, B. 7-Apr, C. 13-Jul, D. 13-30
D: 13-30
Answer: D: 13-30 
Explanation: D i.e. 13-30