Geometrically describe the column space of the matrix as (the set of position vectors for) a point, a line, a plane, all of R³.
(a) ([1,0,0],[0,-1,0],[1,0,0])
(b) ([1,2],[2,4],[3,6])
(c) ([0,0],[0,0],[0,0])
(d) ([1,0,0],[0,1,0],[0,0,1])