Correct Option: D

STD service commissioned between Kanpur and Lucknow in 1960.Subscriber Trunk Dialing (STD) service, started in 1960, is now available in more than 19500 stations in the country. All the district headquarters and more than 97 per cent of the Subdivisional headquarters are having STD facility. International Subscriber Dialing Services started in 1976 between Mumbai and London is now available from every corner of the country to almost all the countries in the world.