The time to complete task B, ts, is a constant (4 days), ta can take as long as 10 days, but can be shortened by assigning additional resources to the task. For every unit of additional resource assigned to task A, the completion time reduces by half a day. Let XA denote the number of additional resources assigned to task A (clearly XA >=0). Due to budget constraints we can assign at most 7 additional units to task A. Which of the following is correct formulation for the linear program that minimizes the project time subject to these constraints? Select one: a. Min z ta = 10 - XA/2 to = 4 XA = 0 Z = ta + to 0 b. Min Z ta = 10 - XA/2 to = 4 XA = 0 Z = 0 Z >=tA Z >=ts d. Min Z ta = 10 - XA/2 te = 4 XA = 7 XA >= 0 Z = max(ta, tp)