Use the Gauss-Jordan Method to Solve the System of Equations $$\begin{aligned}3 x - 7 y - z & = - 28 \\x - 9 y + 9 z & = - 28 \\3 x + y + z & = 34\end{aligned}$$

Multiple Choice

Use the Gauss-Jordan method to solve the system of equations. If the system has infinitely many solutions, let the last
variable be the arbitrary variable.
- $$\begin{aligned}3 x - 7 y - z & = - 28 \\x - 9 y + 9 z & = - 28 \\3 x + y + z & = 34\end{aligned}$$

A) $\{ ( - 8,7,16 ) \}$
B) $\varnothing$
C) $\{ ( 8,7,3 ) \}$
D) $\{ ( 8,3,7 ) \}$