If `A =((1,0,0),(2,1,0),(3,2,1)) u_(1) and u_(2)` are the column matrices such
that `Au_(1) = ((1),(0),(0))and Au_(2) = ((0),(1),(0))" then " u_(1) + u_(2)` is equal to
A. `({:(-1),(-1),(0):})`
B. `({:(1),(-1),(-1):})`
C. `({:(-1),(1),(0):})`
D. `({:(-1),(1),(-1):})`