Cho hai tập hợp A={1;2;3;7}, B={2;4;6;7;8}

A. $A\cup B=\left\{2;7\right\},A\cap B=\left\{4;6;8\right\}$

B. $A\cap B=\left\{2;7\right\},A\backslash B=\{1;3\}$

C. A\B={1;3}, B\A={2;7}

D. A\B={1;3}, $A\cup U=\left\{1;3;4;6;8\right\}$