D — Indian Railways
Indian Railways is owned and operated by the government, making it a public sector enterprise. Birla Cement, TISCO, and Reliance Industries are privately owned companies.
The passage directly states: "Railways or post office is an example of the public sector whereas companies like Tata Iron and Steel Company Limited (TISCO) or Reliance Industries Limited (RIL) are privately owned." Birla Cement is also a private company. For MCQs, one correct option with a brief reason scores full marks.