Which of the following is the inverse of the relation {(1, 5), (2, 6), (1, 7), (4, 8)}? a.{(1, 5), (2, 6), (7, 1), (8, 4)}b.{(5, 1), (6, 2), (7, 1), (8, 4)}c.{(2, 6), (1, 5), (8, 4), (7, 1)}d.{(1, 7), (1, 5), (2, 6), (8, 4)}