Using C to represent consumption, I to represent investment, G to represent government spending, S to represent saving, X to represent exports, and M to represent imports, aggregate expenditures can be represented by which of the following equations?
a. C + I + G + (X + M)
b. (C - S) + G + (X - M)
c. C + I + G + (X - M)
d. C + I + G + (X - M) - S
