Which one of the following statements about network diagrams is TRUE?
◦ In an activity-on-node diagram, "events" are used to denote the end points of arcs.
◦ In an activity-on-node diagram, the nodes depict precedence relationships as well as activities.
◦ In an activity-on-arc diagram, there is never a need to use dummy activities.
◦ In an activity-on-arc diagram, the arcs depict the activities as well as the precedence relationships.