3. Select the statements which are true. (6 pts) Select one or more: a. In an integer program, the number of solutions is always lesser or equal than the number of constraints. b. In an integer program, relaxing the the integrality restriction on the decision variables does not always change the optimal solution. c. In an integer program, the number of solutions is always greater than the number of constraints. d. In an integer program, if a solution exists, the optimal solution cannot have fractional values. 4. Consider the optimisation problem below: maximise 2.21 + 3.22 - 13 subject to: X1 + x2