This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
For congenital obstruction of nasolacrimal duct, probing is done at what age? 
Select and explain. 
A. 2 months, B. 6 months, C. 10 months, D. 14 months
B: 6 months
Answer: B: 6 months 
Explanation: Probing of congenital nasolacrimal duct blockade with bowman's Probe *It should be performed, in case the condition is not cured by the age of 3-4 months. *Some surgeons prefer to wait till the age of 6 months. *It is usually performed under general anaesthesia. *While performing probing, care must be taken not to injure the canaliculus. Ref: Khurana 7th/e p.410