Help please!! Thank you

Answer:
D. 6
Step-by-step explanation:
here, as given set Q consists { 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36}
and set Z contains {3, 6, 9, 12, 15, 18, 21,24, 27, 30, 33, 36, .... }
so be comparing both, we can see that the numbers 6, 12, 18, 24, 30 and 36 is repeated.