Question

Which of the following relations is the reflexive relation over the set {1, 2, 3, 4}?

(a) {(0,0), (1,1), (2,2), (2,3)}

(b) {(1,1), (1,2), (2,2), (3,3), (4,3), (4,4)}

(c) {,(1,1), (1,2), (2,1), (2,3), (3,4)}

(d) {(0,1), (1,1), (2,3), (2,2), (3,4), (3,1)

This question was addressed to me in an online interview.

Question is from Relations topic in chapter Relations of Discrete Mathematics

Answer 1

The correct option is (b) {(1,1), (1,2), (2,2), (3,3), (4,3), (4,4)}

For explanation I would say: {(1,1), (1,2), (2,2), (3,3), (4,3), (4,4)} is a reflexive relation because it contains set = {(1,1), (2,2), (3,3), (4,4)}.