In an open economy, the national income (Y) of the economy is (C, I, G, X, M stand for Consumption, Investment, Government expenditure, total exports and total imports respectively)—
1
Y = C + l + G + X
2
Y = C + I + G - X + M
3
Y = C + I + G + (X - M)
4
Y = C + I - G + X - M