Which of the following options is correct about the relation given by r={(1,2),(2,2),(2,1),(1,1),(3,3)}on the set S={1,2,3}?
a) rr is reflexive, symmetric, and transitive
b) rr is reflexive and symmetric but not transitive
c) rr is reflexive but not symmetric or transitive
d) rr is symmetric and transitive but not reflexive