Which One of the Following Statements About Network Diagrams Is

Which one of the following statements about network diagrams is TRUE?

A) In an activity- on- arc diagram, the arcs depict the activities as well as the precedence relationships.
B) In an activity- on- node diagram, "events" are used to denote the end points of arcs.
C) In an activity- on- arc diagram, there is never a need to use "dummy" activities.
D) In an activity- on- node diagram, the nodes depict precedence relationships as well as activities.