The correct option is B 1967-68
The green revolution was launched in 1967-68. In the year 1966 High Yielding Varieties Program (HYVP) was introduced in the Kharif season. After this program, the production of food grains in 1967-68 was 25% higher than that of 1966-67. This increase was more than the increase recorded the preceding 16 years of the plan period, so this time period is termed as green revolution.