Find the general solution of the system whose augmented matrix is given below.

$\left[\begin{array}{cccccc}1& -2& 0& -1& 0& -7\\ 0& 1& 0& 0& -6& 7\\ 0& 0& 0& 1& 8& 7\\ 0& 0& 0& 0& 0& 0\end{array}\right]$

Select the correct choice below and, if necessary, fill in the answer boxes to complete your answer.

A$.$

B$.$

$x_1=$

$x_{2}is$ free

$x_3=$

$x_{4}is$ free

$x_{5}is$ free

C$.$

$x_1=$

$x_2=$

$x_{3}is$ free

$x_4=$

$x_{5}is$ free

D$.$

The system is inconsistent.