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: Ophthalmology
Length of naso lacrimal duct is 
Select and explain. 
A. 9 mm, B. 10 mm, C. 11 mm, D. 12 mm
D: 12 mm
Answer: D: 12 mm 
Explanation: Nasolacrimal duct is about 12 - 18 mm long.