Constraint A $3 X_{1}+X_{2} \geq 90$ Constraint B $3 X_{1}+2 X_{2} \leq 120$

Multiple Choice

Constraint A: $3 X_{1}+X_{2} \geq 90$ Constraint B: $3 X_{1}+2 X_{2} \leq 120$ Constraint C: $X_{1}-X_{2} \geq 0$
All variables are required to be non-negative. Let the objective function be Max: $X_{1}+X_{2}$ Non-binding constraint corresponding to the optimal solution in this problem will be

A) constraint A
B) constraint B
C) constraint $\mathrm{C}$
D) both $\mathrm{A}$ and $\mathrm{B}$
E) no redundant constraint