Consider the Augmented Matrix $\left[ \begin{array} { l l : l } 1 & - 1 & 2 \\8 & - 6 & 4\end{array} \right]$

Consider the augmented matrix $\left[ \begin{array} { l l : l } 1 & - 1 & 2 \\8 & - 6 & 4\end{array} \right]$ . Which of the following matrices shows the elementary row operation $- 8 R _ { 1 } + R _ { 2 }$ ?

A) $\left[ \begin{array} { c c : c } 1 & - 1 & 2 \\0 & - 14 & - 12\end{array} \right]$
B) $\left[ \begin{array} { l l : l } 1 & - 1 & 2 \\0 & - 2 & 20\end{array} \right]$
C) $\left[ \begin{array} { c c : c } 1 & - 1 & 2 \\0 & 2 & - 12\end{array} \right]$
D) none of these