This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth, Subject name: Pediatrics
'Nocturnal enuresis' refers to involuntary urination at night beyond the age of? 
Select and explain. 
A. 2 years, B. 3 years, C. 4 years, D. 5 years
D: 5 years
Answer: D: 5 years 
Explanation: 'Nocturnal enuresis' refers to involuntary urination at night beyond the age of 5 years Normal milestones: 18 months: Dry during daytime 3 years: Dry at night