Let $A$ and $B$ be two sets. Then

- A
$A \cup B \subseteq A \cap B$

- B
$A \cap B \subseteq A \cup B$

- C
$A \cap B = A \cup B$

- D
None of these

If $A, B$ and $C$ are any three sets, then $A -(B \cup C)$ is equal to

Find the union of each of the following pairs of sets :

$A = \{ x:x$ is a natural number and $1\, < \,x\, \le \,6\} $

$B = \{ x:x$ is a natural number and $6\, < \,x\, < \,10\} $

If $A$ and $B$ are any two sets, then $A \cup (A \cap B) $ is equal to

Find the union of each of the following pairs of sets :

$A = \{ x:x$ is a natural number and multiple of $3\} $

$B = \{ x:x$ is a natural number less than $6\} $

If $X$ and $Y$ are two sets such that $X$ has $40$ elements, $X \cup Y$ has $60$ elements and $X$ $\cap\, Y$ has $10$ elements, how many elements does $Y$ have?