Macroeconomists cannot conduct controlled experiments, such as testing various tax and expenditure policies, because:

 The correct answer is :  Because they must make use of the data history gives them

Explanation:  Macroeconomics is the study of the economy as a whole. Macroeconomic models consist of making different assumptions to explain different aspects of macroeconomics. Macroeconomics is based on microeconomic fundamentals.

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer

1. artillery

2. jose san martin

3.their economies remained dependent on outside powers.

4. drafted new economies

5. democracies have replaced dictatorships