Answer :

Hagrid
The correct answer to this question is letter "c) how to make good decisions within an economy. " William Poole believes economics should be taught in schools because students will learn how to make good decisions within an economy. 

Here are the choices:
a) how economics helps achieve dreams.
b) why economics is a good career choice.
c) how to make good decisions within an economy. 
d) why studying a global economy is important