The ‘Suvarna Karnataka’ year was celebrated to mark:

25 years of Karnataka's formation
50 years of Karnataka's formation
100 years since Mysore Kingdom
50 years of Indian independence

The correct answer is: B) 50 years of Karnataka’s formation.

Karnataka is a state in southern India. It was formed on 1 November 1956, by merging the Kannada-speaking areas of the erstwhile Bombay Presidency, Hyderabad State, Mysore State, and Madras State. The year 2006 was celebrated as Suvarna Karnataka (Golden Karnataka) to mark the 50th anniversary of the state’s formation.

The other options are incorrect. Option A is incorrect because Karnataka was formed in 1956, not 1981. Option C is incorrect because the Mysore Kingdom was founded in 1399, not 1956. Option D is incorrect because India gained independence in 1947, not 1956.