问题如下：
The policymaker of Country M decides to increase the government spending and taxes at the same amount and at the same time. The aggregate demand of Country M is most likely to:
选项：
A.decrease.
B.keep constant.
C.increase.
解释：
C is correct. The balanced budget multiplier is positive due to a higher government spending multiplier than tax multiplier. Although the amount of government spending is the same as taxes, the net effect on aggregate demand is positive.
考点：乘数效应
解析：尽管政府支出与税收相同，但是由于政府支出乘数高于税收乘数，因此平衡预算乘数为正，所以对总需求的净影响是正的。
增加支出或者增税是怎么影响到aggregate demand的呢？
