Indian Railways is the largest public sector undertaking (PSU) in India. It operates one of the largest railway networks in the world and employs millions of people. The organization plays a significant role in the economic development of India by providing affordable and efficient transportation across the country.
Step 1: Indian Railways as the largest PSU
Indian Railways operates and manages more than 65,000 kilometers of track and serves over 8 billion passengers annually. It is a government-owned corporation and an essential part of India's infrastructure.
Step 2: Conclusion
Thus, the largest public sector undertaking in India is Indian Railways.
Final Answer: Indian Railways.