The correct answer is: 1980-81.
The 10+2+3 system was introduced by the State Government of Haryana in 1980-81. The system is a three-stage system of education, with 10 years of schooling followed by two years of higher secondary education and three years of undergraduate education. The system was introduced in order to improve the quality of education in the state and to make it more relevant to the needs of the economy.
Option A is incorrect because the 10+2+3 system was introduced in 1980-81, not 1976-77.
Option B is incorrect because the 10+2+3 system was introduced in 1980-81, not 1988-89.
Option C is incorrect because the 10+2+3 system was introduced in 1980-81, not 1985-86.