Let S be the set of all real numbers. Then, the relation R = {(a, b) : 1 + ab > 0} on S is
A. Reflexive and symmetric but not transitive
B. Reflexive and transitive but not symmetric
C. Symmetric and transitive but not reflexive
D. Reflexive, transitive and symmetric
Answer:A
Let S be the set of all real numbers. Then, the relation R = {(a, b) : 1 + ab > 0} on S is
A. Reflexive and symmetric but not transitive B. Reflexive and transitive but not symmetric C. Symmetric and transitive but not reflexive D. Reflexive, transitive and symmetric