we can also eliminate options here. By adding first 2 inequalities, we get, $3x_1 + 3x_2 \leq 9$.

It can also be written as: $x_1+z \leq 9$. So, $z \leq 9\; – \;x_1$

Since, $x_1 \geq 0$, So, $z\leq 9$. So, from given options, we can eliminate first 3 options.

It can also be written as: $x_1+z \leq 9$. So, $z \leq 9\; – \;x_1$

Since, $x_1 \geq 0$, So, $z\leq 9$. So, from given options, we can eliminate first 3 options.