In India, the inflation is primarily measured by the Wholesale Price Index (WPI) which is the correct answer as per the options. It`s an indicator that measures the average change in price of goods traded in bulk by wholesale businesses. The WPI highlights the price movement of goods in the wholesale market, before the retail level, thus providing insights into the likely retail price changes.

Option 2, the Consumer Price Index (CPI) for urban non-manual workers, and option 3, the CPI for agricultural workers, are sub-categories of CPI, which measure changes in the price level of a basket of consumer goods and services purchased by specific groups. However, these are not primary measures of inflation in India.

Option 4, National Income Deflation, refers to a situation where national income decreases with a decrease in price levels, but this term is not used to measure inflation directly but to understand the relationships of national income during periods of changing price levels.