The correct answer is option 2, National Hydroelectric Power Corporation Ltd.

To understand why option 2 is the correct answer, let`s look at the other options:

Option 1: Bharat Electronics Ltd is a Defence Public Sector Undertaking (DPSU). It is an Indian state-owned aerospace and defence company, primarily involved in the design, manufacture, and supply of electronic equipment for the Indian Armed Forces.

Option 3: Bharat Earth Movers Ltd, commonly known as BEML, is also a Defence Public Sector Undertaking. It is a manufacturer of a variety of heavy equipment for sectors like mining, construction, and defence.

Option 4: Mazgaon Dock Ltd is a Defence Public Sector Undertaking. It is a shipyard in Mumbai, India, known for building warships and submarines for the Indian Navy.

Therefore, the correct answer is option 2, National Hydroelectric Power Corporation Ltd, as it is not a Defence Public Sector Undertaking. It is a public sector company primarily engaged in the generation of hydroelectric power.

Alert - the correct answer should be: 2, National Hydroelectric Power Corporation Ltd