For the set A={1,2,3}, which of the following relations on A is reflexive and symmetric but not transitive?
a) {(1,1),(2,2),(3,3),(1,2),(2,1)}
b) {(1,1),(2,2),(3,3),(1,2),(2,1),(2,3)}
c) {(1,1),(2,2),(3,3),(1,2),(2,1),(2,3),(3,2)}
d) {(1,2),(2,1),(2,3),(3,2)}