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: ENT
The sleep apnea syndrome is defined as - 
Select and explain. 
A. 30 or more episodes of apnea during 12 hours sleep, B. 28 or more episodes of apnea during 7 hours sleep, C. 30 or more episodes of apnea during 7 hours sleep, D. 30 or more episodes of apnea during 10 hours sleep
C: 30 or more episodes of apnea during 7 hours sleep
Answer: C: 30 or more episodes of apnea during 7 hours sleep 
Explanation: None