XYZ Inc Produces Two Types of Printers - Regular and High-Speed

XYZ Inc. produces two types of printers - regular and high-speed. Net contribution is $\$ 50.00$ per unit from regular and $\$ 70.00$ per unit from high-speed. Regular uses 2 units of recycled plastic per unit, and high-speed uses 1 unit of recycled plastic per unit of production. XYZ is committed to using at least 5,000 units of recycled plastic per month. A critical machine is needed to manufacture the printers. Each unit of regular requires 10 units of time in this machine and each unit of high-speed requires 3 units of time in this machine. The total time available in this machine per month is 15,000 units. Let $X_{1}$ be the number of units of regular produced per month and $X_{2}$ the number of units of high-speed produced per month. Imposing both of these constraints and non-negativity constraints, the optimal solution to this problem (assuming the first number in parenthesis is $X_{1}$ and the second number in parenthesis is $X_{2}$ ) will be

A) $(0,0)$
B) $(2500,0)$
C) none exists
D) $(0,5000)$
E) $(1500,0)$