Explanation:

- The decadal growth percentage is a measure of increase in population over ten years.

- During 1981-1991, the growth was 23.86% - this shows a significant increase in population during that decade.

- In 1991-2001, there was a decline in this growth rate.

- Among the options, we're looking for a noticeable decline from 23.86%.

- Option 1: 20.34% - A clear reduction, showing a significant decline.

- Option 2: 19.34% - An even sharper decrease, noticeable but potentially too low.

- Option 3: 22.34% - A decline, but relatively minor.

- Option 4: 21.34% - A moderate decline that could be considered significant.