单项选择题

The government, when it places high duties on imported commodities of classes C and D,______.

A.raises the price of commodities produced by A and B
B.is, in effect, taxing the workers in A and B
C.raises the wages of workers in C and D at the expense of the workers in A and B
D.does not affect the productivity of the workers in A and B, although the wages of these workers are reduced