Ans: D
$\begin{array}{cl}
& \left(\dfrac{1}{9^{555}} \right) 3^{444} \\
= & \left(\dfrac{1}{(3^2)^{555}} \right) 3^{444} \\
= & \dfrac{1}{3^{2 \times 555 – 444}} \\
= & \dfrac{1}{3^{666}}
\end{array}$
$\begin{array}{cl}
& \left(\dfrac{1}{9^{555}} \right) 3^{444} \\
= & \left(\dfrac{1}{(3^2)^{555}} \right) 3^{444} \\
= & \dfrac{1}{3^{2 \times 555 – 444}} \\
= & \dfrac{1}{3^{666}}
\end{array}$
