Ans: A
$\begin{array}{cl}
& 4^{n+2}3^{2n+4} \\
= & (2^2)^{n+2} 3^{2n+4} \\
= & 2^{2n+4} 3^{2n+4} \\
= & (2\times 3)^{2n+4} \\
= & 6^{2n+4}
\end{array}$
