Step 1: Understanding Dearness Allowance.
Dearness Allowance is a cost of living adjustment allowance paid to government employees to offset the impact of inflation. It is typically calculated using the Consumer Price Index (CPI), which measures the average change over time in the prices of goods and services typically consumed by households.
Step 2: Conclusion.
Therefore, the Dearness Allowance is based on the Consumer Price Index (CPI).
Final Answer: Consumer price index.