India's Five Year Plans each have a recorded average GDP growth rate, based on data published by the Planning Commission and the CSO. Comparing the plans mentioned in the options: the Sixth Plan (1980 to 1985) grew at about 5.7% a year, the Seventh Plan (1985 to 1990) grew at about 6.0% a year, the Eighth Plan (1992 to 1997), the first plan after the 1991 economic reforms, grew at about 6.8% a year, and the Ninth Plan (1997 to 2002) slowed to about 5.4% a year due to the Asian financial crisis and other shocks. Let's check each option against these figures.
Since the Eighth Plan recorded the fastest average GDP growth among these four plan periods, it is the correct answer.
Let's summarize:
The answer is option (3), Eighth Plan.