Let R and S be relations defined on the set {2,5,6,3}.
R = {(2,3),(6,6),(2,6),(6,5),(2,3),(6,6),(2,6),(6,5)}
S = {(2,3),(6,3),(5,3),(5,6),(2,3),(6,3),(5,3),(5,6)}
Answer each of the following questions:
Which of the following statements is true about the relations R and S ?

a) R is a function, while S is not.
b) R is reflexive, while S is not.
c) R and S have the same domain.
d) R and S are both symmetric relations.