Which of these statements is NOT true about CPM and PERT?
a. In a project, if the duration of the activities is known we use PERT, if the duration is not known we use CPM.
b. CPM and PERT have been used in scheduling construction projects,
c. The predecessors are a set of activities that must be completed before an activity.
d. CPM and PERT have been used in building ships.