{1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}
{1, 2, 3, 5, 6, 8, 12, 15}
{2, 4, 5, 9, 12, 15}
{1, 5, 6, 7, 8, 9, 12, 15}
Correct answer is A
{A ∪ B ∪ C}
{A ∪ B} = {1, 3, 5, 7, 9, 12, 15}
∪ C={2,4,6,8}
{A ∪ B} ∪ C = {1, 3, 5, 7, 9, 12, 15} ∪ {2, 4, 6, 8}
= {1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}
{A ∪ B} ∪ C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15}