Use the Two-Stage Method to Solve $x_{1} \geq 0$ And $x_{2} \geq 0$

Multiple Choice

Use the two-stage method to solve.
-Find $x_{1} \geq 0$ and $x_{2} \geq 0$ such that
$2 x_{1}+x_{2} \geq 12$
$\mathrm{x}_{1}+4 \mathrm{x}_{2} \leq 36$
And $\mathrm{z}=4 \mathrm{x}_{1}+3 \mathrm{x}_{2}$ is maximized.

A) $x_{2}=9, x_{1}=0, z=39$
B) $x_{1}=36, x_{2}=0, z=144$
C) $x_{1}=12, x_{2}=0, z=48$
D) $x_{1}=32, x_{2}=1, z=131$