1. The source and sink of a maximum flow problem have conservation of flow constraints. True or False?
2. A nonlinear function may contain a product of two variables. True or False?
3. In a binary integer problem with 2 mutually exclusive alternatives, X1 and X2, the following constraint needs to be added to the formulation if one alternative must be chosen:
A. X1 + X2 <= 1
B. X1 + X2 = 1
C. X1 - X2 <= 1
D. X1 - X2 = 1
E. None of the above