Let $A$ and $B$ be two sets. Then
$A \cup B \subseteq A \cap B$
$A \cap B \subseteq A \cup B$
$A \cap B = A \cup B$
None of these
Let $A$ and $B$ be subsets of a set $X$. Then
If $A=\{3,6,9,12,15,18,21\}, B=\{4,8,12,16,20\},$ $C=\{2,4,6,8,10,12,14,16\}, D=\{5,10,15,20\} ;$ find
$D-B$
Which of the following pairs of sets are disjoint
$\{1,2,3,4\}$ and $\{ x:x$ is a natural number and $4\, \le \,x\, \le \,6\} $
If $X=\{a, b, c, d\}$ and $Y=\{f, b, d, g\},$ find
$X-Y$
If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find
$A \cup B$