Let U = {1, 2, 3, 4} and S = {1, 2}. We define the binary relation R on the nonempty subsets of U as follows. R = {(A, B) : A - S = B; A, BCU} (a) [2 marks] Is R reflexive? If you believe it is true, then prove your answer; other- wise, give a counterexample. (b) [6 marks] Is R symmetric? Again, prove or disprove. (c) [6 marks] Is R transitive? Again, prove or disprove. (d) [6 marks] Is R antisymmetric? Again, prove or disprove