If $A$ and $B$ are two sets, then $A × B = B × A$ iff
$A \subseteq B$
$B \subseteq A$
$A = B$
None of these
If $A = \{ 2,\,4,\,5\} ,\,\,B = \{ 7,\,\,8,\,9\} ,$ then $n(A \times B)$ is equal to
If $A = \{2, 3, 5\}, B = \{2, 5, 6\},$ then $(A -B) × (A \cap B)$ is
If $P,Q$ and $R$ are subsets of a set $A$, then $R × (P^c \cup Q^c)^c =$
If two sets $A$ and $B$ have $99$ elements in common, then the number of elements common to the sets $A \times B$ and $B \times A$ is equal to
If $A = \{ x:{x^2} - 5x + 6 = 0\} ,\,B = \{ 2,\,4\} ,\,C = \{ 4,\,5\} ,$ then $A \times (B \cap C)$ is