og11 83题，求指教

most state constitutions now mandate that the state budget be balanced each year
            

a mandate that the state budget be balanced

b mandate the state budget to be balanced

c mandate that the state budget will be balanced

d have a mandate for a balanced state budget

e have a mandate to balance the state budget

答案是a，b错在那里了？请指教

难道：mandate the state budget  be balanced

就是正确了的吗？

我想说的是进讨论贴看看。