The correct answer is (b), 31st March, 1973.
Kumaun Mandal Vikas Nigam and Garhwal Mandal Vikas Nigam were established on 31st March, 1973 by the Uttar Pradesh government to promote the economic development of the Kumaon and Garhwal regions of Uttarakhand. The two corporations were merged in 2000 to form the Uttarakhand State Industrial Development Corporation.
Option (a), 30th March, 1971 is incorrect because the Kumaun Mandal Vikas Nigam and Garhwal Mandal Vikas Nigam were established on 31st March, 1973.
Option (c), 31st March, 1976 is incorrect because the Kumaun Mandal Vikas Nigam and Garhwal Mandal Vikas Nigam were established on 31st March, 1973.
Option (d), 30th March, 1980 is incorrect because the Kumaun Mandal Vikas Nigam and Garhwal Mandal Vikas Nigam were established on 31st March, 1973.