The sum of first 20 terms of the sequence

$\frac{7}{81}\left(179-10^{-20}\right)$

$\frac{7}{9}\left(99-10^{-20}\right)$

$\frac{7}{81}\left(179+10^{-20}\right)$

$\frac{7}{9}\left(99-10^{-20}\right)$