The closed form for the $n^{th}$ term of the sequence with generating function $\frac{1}{1-ax}$ is $a^n$
The closed form for the $n^{th}$ term of the sequence with generating function $\frac{x}{1-ax}$ is $a^{n-1}$
$\therefore \frac{9x}{1-2x}$ corresponds to $9.2^{n-1}$ and $\frac{x}{1-x}$ corresponds to $1.$
Adding them we get the answer as option D.