B对的原因在于现在的tax law 是base on all retail items sold的,所以如果新开一个shopping mall, 就必然会增加sold retail item, thereby increasing tax
而d强调的是在property tax下面,有一部分人不交tax。 然而要support 题目一个隐含条件是:在新的tax law下,这部分人会increase their retail sales so that total tax collected can be increased. however, we cannot conclude from the text that these people will increase their purchasing power.