Network notation (AOA): On a traditional activity-on-arrow network diagram, an activity is represented by which symbol?

Introduction / Context:
Project networks can be drawn using activity-on-arrow (AOA) or activity-on-node (AON) conventions. Exams often test recognition of which graphical element represents an activity under each convention.

Given Data / Assumptions:

• AOA convention is assumed unless otherwise specified.
• Events (start/finish points) are shown as nodes (circles), activities as arrows.
• Logical precedence is represented by arrow direction.

Concept / Approach:
In AOA, the activity is the arrow and the event is the circle. In AON, the activity is the node (box), and precedence is the arrow connecting nodes. The question explicitly targets the AOA meaning of “activity.”

Step-by-Step Solution:

Verification / Alternative check:
Any AOA example (e.g., CPM in early texts) shows activities on arrows, events as nodes labeled i and j.

Why Other Options Are Wrong:
Circle denotes event; diamond/rectangle are not standard AOA activity symbols; a line without an arrowhead loses directionality and is not the conventional representation.

Common Pitfalls:
Confusing AOA with AON; failing to notice arrowheads that indicate precedence.

Final Answer:
An arrow (directed line) between events