The following questions refer to the CRT Technologies project selection example presented in this chapter. Formulate a constraint to implement the conditions described in each of the following statements. a. Out of projects 1, 2, 4, and 6, CRT's management wants to select exactly two projects. b. Project 2 can be selected only if project 3 is selected and vice-versa. c. Project 5 cannot be undertaken unless both projects 3 and 4 are also undertaken. d. If projects 2 and 4 are undertaken, then project 5 must also be undertaken