The critical path is the path in the project network diagram with the longest duration. In project management, a critical path is the sequence of project network activities which add up to the longest overall duration. This determines the shortest time possible to complete the project. Any delay of an activity on the critical path directly impacts the planned project completion date (i.e. there is no float on the critical path). This project actually has two critical paths. Path ACGIJ takes 23 days. Path ACGHJ also takes 23 days. When Activity I decreases by three days the critical will still take 23 days to complete as Path ACGHJ remains a critical path.

Answer option A is incorrect. The duration of the critical path did not increase.

Answer option D is incorrect. The duration of the path ACGIJ will decrease to 20 days but the critical path will remain at 23 days.

Answer option B is incorrect. The critical path did not reduce to 17 days.