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

If $A = \{3, 6, 9, 12, 15, 18, 21\}$,$B = \{4, 8, 12, 16, 20\}$,$C = \{2, 4, 6, 8, 10, 12, 14, 16\}$,and $D = \{5, 10, 15, 20\}$,find $B - A$.

Given the sets $A = \{1, 2, 3\}$,$B = \{3, 4\}$,and $C = \{4, 5, 6\}$,find $A \cup (B \cap C)$.

If $A = \{3, 6, 9, 12, 15, 18, 21\}$,$B = \{4, 8, 12, 16, 20\}$,$C = \{2, 4, 6, 8, 10, 12, 14, 16\}$,and $D = \{5, 10, 15, 20\}$,find $D - A$.

If $A = \{2, 3, 4, 8, 10\}, B = \{3, 4, 5, 10, 12\}, C = \{4, 5, 6, 12, 14\}$,then $(A \cup B) \cap (A \cup C)$ is equal to:

Which of the following pairs of sets are disjoint?
${1, 2, 3, 4}$ and ${x : x \text{ is a natural number and } 4 \le x \le 6}$