P = {2, 3, 5, …, 13}
Q = {7, 6, 5, …, 1}
R = {2, 4, 6, …, 14}
P ∩\cap∩ (Q ∪\cup∪ R)= …
{2, 3, 5, 7}
{2, 3, 4, 5, 6, 7, 11, 13}
{2, 5}
{2, 3, 5, 9}