The universal set U is the set of all odd numbers less than 20 and set A = {x : x is an odd multiple of 3 and x < 20}. Find complementary set A'.
1
A' = {1, 5, 11, 13, 17, 19}
2
A' = {1, 5, 7, 11, 13, 17, 19}
3
A' = {1, 19}
4
A' = {1, 2, 5, 7, 8, 11, 13, 16, 17, 19}