Final answer:
Gross Domestic Product (GDP) is the most useful measure for comparing the economic growth of countries, as it encompasses the total value of goods and services produced in a nation within a given period.
Step-by-step explanation:
The most useful measure of economic growth for comparing countries is the Gross Domestic Product (GDP). GDP assesses the monetary value of all finished goods and services produced within a country's borders in a specific time period and reflects the size and health of a country's economy. It is often used to compare the economic performance of different countries. Other indicators like the Consumer Price Index (CPI), Unemployment Rate, and Inflation Rate provide valuable information on a country's economic conditions but are not as comprehensive as GDP for measuring and comparing economic growth.
Economists often adjust GDP for inflation to get the real GDP, which gives a more accurate reflection of an economy's size and how much it has grown from one period to another. Ultimately, the percentage change in real GDP is what indicates the rate of economic growth, with a rate of more than 3% generally signifying a healthy economy. Therefore, GDP, specifically real GDP, is the preferred metric for evaluating and comparing the economic growth rates of different countries.