Project scheduling (CPM/PERT): Which statements correctly describe a network diagram's basic notation for activities and events?

Introduction / Context:
Network diagrams are the backbone of Critical Path Method (CPM) and PERT. They visualise project activities, their logical order, and interdependencies so planners can compute floats, detect the critical path, and manage time-risk trade-offs.

Given Data / Assumptions:

• Activity-on-Arrow (AOA) convention is referenced in the statements.
• Each activity has a defined start and finish event.
• Dummy activities (zero duration) sometimes maintain logic only.

Concept / Approach:
In AOA networks, events (milestones) are nodes; activities are arrows connecting start and finish events. The arrow tail marks the activity's commencement, and the arrow head meets the event that signifies completion, enabling forward/backward passes to compute early and late times.

Step-by-Step Solution:

Verification / Alternative check:
Compare with Activity-on-Node (AON) notation where nodes are activities; despite visual differences, logical meaning for starts/finishes remains consistent.

Why Other Options Are Wrong:
Each of (a), (b), and (c) is correct in AOA; therefore “All of the above” is the only comprehensive answer.

Common Pitfalls:
Mixing AOA and AON conventions; misusing dummy activities; reversing arrow directions leading to logic errors.

Final Answer:
All of the above