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
A 60 year old man presented with watering from his left eye since 1 year. Syringing revealed a patent drainage system. Rest of the ocular examination was normal. A provisional diagnosis of lacrimal pump failure was made. Confirmations of the diagnosis would be by: 
Select and explain. 
A. Dacryoscintigraphy, B. Dacryocystography, C. Pressure syringing, D. Canaliculus irrigation test
A: Dacryoscintigraphy
Answer: A: Dacryoscintigraphy 
Explanation: Ans. Dacryoscintigraphy