Which country has the largest ambulance service?

Which country has the largest ambulance service?

سب سے بڑی ایمبولینس سروس کس ملک میں ہے؟
Explanation

The Edhi Foundation welfare organization based in Pakistan.

It was founded by Abdul Sattar Edhi in 1951,

Abdul Sattar Edhi served as the head of the organization until his death on 8 July 2016.

The Edhi Foundation is headquartered in the city of Karachi.

*****

Pakistan has the world's largest ambulance service – (Guinness record) 

The Edhi Foundation also has a number of branches in various countries including UK, Canada, Japan, US and Bangladesh where they provide relief to refugees.