Provide an Appropriate Response $$\left[ \begin{array} { r r r | r } 1 & - 15 & 7 & 19 \\0 & 1 & 14 & - 8 \\0 & - 9 & 20 & - 2\end{array} \right]$$

Multiple Choice

Provide an appropriate response.
-Suppose that you are solving a system of three linear equations by the Gauss-Jordan method and obtain the following augmented matrix.
$$\left[ \begin{array} { r r r | r } 1 & - 15 & 7 & 19 \\0 & 1 & 14 & - 8 \\0 & - 9 & 20 & - 2\end{array} \right]$$
What row transformation would you perform next?

A) Multiply row 3 by $\frac { 1 } { 20 }$ .
B) Add 9 times row 1 to $- 15$ times row 3 .
C) Add $- \frac { 1 } { a }$ times row 2 to row 3 .
D) Add 9 times row 2 to row 3 .