A production optimization problem has 4 decision variables and resource b1 limits how many of the 4 products can be produced. Which of the following constraints reflects this fact?
f(X1, X2, X3, X4) < b1
f(X1, X2, X3, X4) >b1
f(X1, X2, X3, X4) = b1
f(X1, X2, X3, X4) < > b1