Which is India's largest public sector undertaking?

Indian Railways (IR) is India's national railway system operated by the Ministry of Railways. It is one of the public facilities given by the government and manages the fourth largest railway network in the world by size, with a route length of 95,981-kilometre (59,640 mi) as of March 2019.
Number of employees‎: ‎1.30 million (2017)
Revenue‎: ‎₹1.97214 trillion (US$28 billion)
Net income‎: ‎₹60.14 billion (US$840 million)
Owner‎: ‎Government of India‎ (100%)