Given the following relations on S = {a, b}: {(a, a)} {(a, b)} {(b, a)} {(b, b)} {(a, a), (a, b)} {(a, a), (b, a)} {(a, a), (b, b)} {(a, b), (b, a) {(a, b), (b, b)} {(b, a), (b, b)} {(a, a), (a, b), (b, a)} {(a, a), (a, b), (b, b)} {(a, a), (b, a), (b, b)} {(a, b), (b, a), (b, b)} {(a, a), (a, b), (b, a), (b, b) Which ones are: a. reflexive? b. symmetric? c. antisymmetric? d. transitive