Which Venn diagram represents the truth of the statement "No policeman is a thief"?

If $A = \{3, 5, 7, 9, 11\}$,$B = \{7, 9, 11, 13\}$,$C = \{11, 13, 15\}$,and $D = \{15, 17\}$,find $A \cap B$.

Find the union of each of the following pairs of sets:
$A = \{1, 2, 3\}, B = \varnothing$

Let $A = \{a, b\}$ and $B = \{a, b, c\}$. Is $A \subset B$? What is $A \cup B$?

If $A = \{ x : x \text{ is a natural number} \}$,$B = \{ x : x \text{ is an even natural number} \}$,$C = \{ x : x \text{ is an odd natural number} \}$,and $D = \{ x : x \text{ is a prime number} \}$,find $B \cap D$.

The simplified switching circuit for the following circuit is