Which component is considered when calculating the consumer price index?

The consumer price index (CPI) is a measure that examines the average change over time in the prices paid by consumers for a basket of goods and services. This selected basket typically includes a variety of items such as food, clothing, rent, healthcare, and transportation. By analyzing the retail prices of these specific goods and services, the CPI provides valuable insight into inflation and the cost of living over time.

The other components listed, like the average wage of workers, gross national product, and level of international trade, do not directly influence the CPI calculation, as they represent broader economic indicators rather than specific price changes for consumer goods and services. Therefore, the retail prices of a selected basket of goods and services is the essential aspect of constructing the consumer price index, making it the correct answer.