A: 12000×(1-30%)×1.2%=100.8(万元)
B: 12000×(1-30%)×1.2%+80×12%=110.4(万元)
C: (12000+400)×(1-30%)×1.2%+80×12%=113.76(万元)
D: (12000+400+600)×(1-30%)×1.2%=109.2(万元)