In critical path analysis, which statement is true?

• A. The shortest path through the network diagram determines the project duration
• B. Slack is always positive on the critical path
• C. The longest path through the network diagram that determines the project duration
• D. All tasks on the critical path have zero duration

Answer: (C)

In critical path analysis, the project finish date is driven by the path through the network diagram that takes the most time to complete. This longest path—the critical path—sets the overall duration because any delay on a task along it will delay the project finish, since there is no slack to absorb that delay. Tasks not on the critical path have slack and can slip without changing the finish date. So the true statement is that the longest path through the network diagram determines the project duration. The other statements don’t fit because the shortest path doesn’t set the finish date, the critical path has zero slack (not positive), and those tasks still have positive durations—they simply have no flexibility in timing.