(Advanced Analysis)Answer the Question on the Basis of the Following $\begin{array} { l } C = 40 + 0.8 Y \\t _ { g } = \overline { I _ { g } } = 40 \\X = \bar { X } = 20 \\M = \bar { M } = 30\end{array}$

(Advanced analysis) Answer the question on the basis of the following information for a private open economy.The letters Y,C,I_g,X,and M stand for GDP,consumption,gross investment,exports,and imports respectively.Figures are in billions of dollars. $\begin{array} { l } C = 40 + 0.8 Y \\t _ { g } = \overline { I _ { g } } = 40 \\X = \bar { X } = 20 \\M = \bar { M } = 30\end{array}$ Refer to the information.International trade in this case:

A) has an expansionary effect on GDP.
B) has a contractionary effect on GDP.
C) has no effect on GDP.
D) is causing inflation in this economy.