The lines (x -2)/1 = (y - 3)/1 = (z - 4)/-k and (x - 1)/k = (y -4)/2 = (z - 5)/ 1 are coplanar if
(a) k = 1 or –1
(b) k = 0 or –3
(c) k = 3 or –3
(d) k = 0 or –1