Consider the following linear programming problem:

Min Z = 21x₁ + 15x₂

Subject to:

4x₁ + 3x₂ 200 (constraint 1)

2x₁ + x₂ 70 (constraint 2)

x₁, x₂ 0

What is the lower limit of the right hand side of the first constraint (q₁)?

a. 47.5

b. 54

c. 140

d. 57.5

e. None of the above