If $A=\left\{x: x=3^n, n \in N\right\}$ and $\left.B=\left(x: x=9^n, n \leq 4\right), n \in N\right\}$ then which of the following is false?

$A \cap B=\{9,81,729,6561\}$

$A=\left\{3^1, 3^2, 3^3, 3^4, 3^5, 3^6\right\} =\{3,9,27,81,243,729\}$

and $B=\left\{9^1, 9^2, 9^3, 9^4\right\}=\{9,81,729,6561\}$

(a) $A \cup B=\{3,9,27,81,243,729,6561\}$

(b) $A \cap B=\{9,81,729\}$

(c) $A-B=\{3,27,243\}$

(d) $A \Delta B=(A-B) \cup(B-A)$

$=\{3,27,243\} \cup\{6561\}=\{3,27,243,6561\}$

Hence (2) is the correct answer.