A circular-flow diagram is a model that a. helps to explain how participants in the economy interact with one another. b. helps to explain how the economy is organized. c. incorporates all aspects of the real economy. d. Both (a) and (b) are correct.

D?

Explanation:

The circular flow diagram is a model of the economy in which the major exchanges are represented as flows of money, goods and services, etc. between economic agents. The flows of money and goods exchanged in a closed circuit correspond in value, but run in the opposite direction.

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