`A=[(1,0,0),(2,1,0),(3,2,1)],` If `U_1,` `U_2,`and `U_3` are columns matrices satisfying. `AU_1=[(1),(0),(0)]`, `AU_2=[(2),(3),(0)]`, `AU_3=[(2),(3),(1)]`and `U` is `3` x `3` matrix whose columns are `U_1,` `U_2,` `U_3`, then answer the folllowing questions:
The sum of the elements of `U^-1` is-

Options

A. `-1`
B. `0`
C. `1`
D. none of these