Heft Company Produces a and B with Contribution Margins Per

Heft Company produces A and B with contribution margins per unit of $40 and $30,respectively.Only 500 labour hours and 300 machine hours are available for production. Time requirements to produce one unit of A and B are as follows:
$\begin{array}{lcc}&\text {Product A }&\text {Product E}\\ \text { Labour hours per unit } &5&2\\ \text { Machine hours per unit } &1&4\\\end{array}$
What is the constraint on machine hours for Heft Company?

A) 1A + 4B $\le$ 300
B) 1A + 4B $\le$ 500
C) 5A + 2B $\le$ 500
D) 40A + 30B $\le$ 500