The correct answer is: C. 1995-96
The base year for measuring national income at constant prices is the year that is used as the reference point for comparing economic data over time. The base year is typically chosen because it was a year of relatively low inflation, so that changes in economic output can be attributed to real changes in production rather than to changes in prices.
In India, the base year for measuring national income at constant prices is 1995-96. This means that all economic data for subsequent years is adjusted to reflect the prices that were in effect in 1995-96. This allows us to compare economic output over time in a meaningful way.
The other options are incorrect because they are not the base year for measuring national income at constant prices in India.