The correct answer is: B. latest allowable time.
The latest allowable time (LT) is the latest time that an activity can be completed without delaying the project’s completion. It is calculated by subtracting the total float from the earliest finish time (EFT).
The earliest allowable time (EA) is the earliest time that an activity can be started without delaying the project’s completion. It is calculated by adding the total float to the earliest start time (EST).
The earliest pass is the earliest time that an activity can be completed. It is calculated by adding the duration of the activity to the earliest start time.
The latest pass is the latest time that an activity can be completed without delaying the project’s completion. It is calculated by subtracting the duration of the activity from the latest finish time.
Therefore, the latest allowable time is the latest time that an event can be delayed without delaying the completion of the entire project in PERT chart.