15. Let P = {4, 6, 8), Q = {1, 3, 9), R = {0, 2, 5) and S = 7).
Which of the following is the universal set of P, Q, R and S?
A. {0, 1, 2, 3, 4, 6, 7, 8, 9} C. {1,2,3,4,5,6,7,8,9)
B. {0, 1, 2, 3, 4, 5, 6, 7, 8} D. {0, 1,2,3,4,5,6,7, 8, 9)​