lx+my+nz=d is the normal form of a plane (II). x/a+y/b+z/c=1 is the intercept form (IV). (r−a)⋅n=0 is a plane through point a with given normal n (I). The combination with λ gives a plane through the intersection of two planes (III). So A-II, B-IV, C-I, D-III.