The correct answer is (c) Consumer Price Index.
The Consumer Price Index (CPI) is a measure of the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. The CPI is a key measure of inflation, and is used to adjust wages, salaries, pensions, and other payments.
The Wholesale Price Index (WPI) is a measure of the average change over time in the prices received by domestic producers for their output. The WPI is not a good measure of inflation, because it does not include the prices paid by consumers.
The Price Index of Industrial Goods (PIG) is a measure of the average change over time in the prices of industrial goods. The PIG is not a good measure of inflation, because it does not include the prices paid by consumers.
The Consumer Price Index is the most common measure of estimating inflation in India because it is a measure of the prices paid by consumers, which is the most relevant measure of inflation for most people.