An increase in interest rates over time would most likely lead to a decrease in the Consumer Price Index (CPI). Higher interest rates typically lead to reduced consumer spending and investment, which can slow down economic activity and reduce inflationary pressures, potentially leading to a decrease in the CPI.
The other options, such as a decrease in the national unemployment rate, an increase in minimum wage, and expansionary fiscal policy, are more likely to contribute to rising demand and potentially increase the CPI.