(a) is shown above in a 3D presentation best viewed with 3D viewers (green/blue filter right eye, red filter left eye). The vector is represented by the line segment OA which is a transverse diagonal in the Cartesian cuboid shown by dotted lines, to illustrate the coords of the point A(-1,2,3).

In the other parts to this question (b) can be similarly drawn using the coords (3,4,2) in place of (-1,2,3). For parts (c) and (d) the coords are in 2D only and can be drawn on the x-y plane as the diagonal of a rectangle instead of a cuboid, rather like the diagonal OB in the picture.