Which of the following two sets are equal?

A.A = {1, 2, 3} and B = {2, 1, 3}
B.A = {1, 2, 4} and B = {1, 2, 3}
C.A = {1, 2} and B = {1}
D.A = {1, 2} and B = {1, 2, 3}​