A firm has prepared the following binary integer program to evaluate a number of potential new capital projects. The firm's goal is to maximize the net present value of their decision while not spending more than their currently available capital, Maxleexl + 126x; + 99X3 + 135X4 5.2\". 156X1 + 269x; + 225X3 + 175X4 5 599 [Constraint 1} X1 + X2 + X3 + X4 2 2[Constraint 2} X2 + X4 5 1[Constraint 3} X2 + X3 2 1[Constraint 4} X1 = X4 {Constraint 5] m: { 1, if project j is selected J 0, otherwise Which of the constraints enforces a contingent relationship? \f