Avenn diagram is shown below: a venn diagram showing two categories, a and b. in the a only circle is 1 and 2, in the b circle is 5 and 6, in the intersection is 3 and 4, and in outside the circles is u what are the elements of (a ∩ b) ' ? {3, 4} {1, 2, 3, 4} {1, 2, 5, 6} {3, 4, 5, 6}

Let
ξ > is a universal set.
A> is a  subsets of ξ
B> is a  subsets of ξ

we know that
ξ = {1, 2, 3, 4, 5, 6}
A = {1, 2, 3, 4} 
B = {3, 4, 5, 6} 

(A ∩ B)' = {elements of ξ which are not in A ∩ B}

and

A ∩ B = {elements which are common to both A and B}
A ∩ B= {3,4} 

therefore
the elements of (A ∩ B) ' ={1,2.5,6}

the answer is the option
{1, 2, 5, 6}