The correct answer is (b). The Rolling Plan was in operation in India from 1978-79 to 1984-85. It was a five-year plan that was revised every year. The main objective of the Rolling Plan was to achieve self-reliance in the economy. The plan was successful in achieving some of its objectives, such as increasing the growth rate of the economy and reducing the import of capital goods. However, it was not able to achieve its goal of self-reliance.
The other options are incorrect. Option (a) is incorrect because the Fourth Five-Year Plan was in operation in India from 1969-74. Option (c) is incorrect because the Sixth Five-Year Plan was in operation in India from 1980-85. Option (d) is incorrect because the Seventh Five-Year Plan was in operation in India from 1985-90.