The POM$-$QM output for the below linear programming problem is:

Maximize Z $=3$X$1+5$X$2$

subject to X$1+3$ X$220$

X$1+$ X$210$

and X$10,$ X$20$

What is the most allowable decrease in the objective function coefficient of X$2$ that will not change the optimal solution?

None of these values

$9$

$5$

$4$

$2$