The correct answer is: c) North Eastern Coalfields.
North Eastern Coalfields Limited (NECL) is a state-owned coal mining company in India. It is a subsidiary of Coal India Limited, the largest coal mining company in the world. NECL was formed in 1985 to take over the coal mining operations of the erstwhile Assam Valley Coalfields Limited. The company has its headquarters in Margherita, Assam.
NECL has three coal mines in Assam: Margherita, Makum, and Lakwa. The company also has a washery at Margherita. The total coal production of NECL in 2019-20 was 2.9 million tonnes.
The other options are incorrect. Bharat Coking Coal Limited is a coal mining company in India that is headquartered in Ranchi, Jharkhand. Oil India Limited is an oil and gas company in India that is headquartered in Duliajan, Assam. Geological Survey of India is a government agency in India that is responsible for geological survey and mapping.