Which of the following terms is used for a schedule compression technique where two activities that were previously scheduled to start sequentially start at the same time?

Fast tracking compresses the project schedule by overlapping activities that were planned to be done sequentially, effectively starting a successor activity before its predecessor is fully complete. This reduces overall duration but increases risk because the downstream activity begins before all required inputs from the upstream activity are available.

'Compressing' is a generic English word and not a recognized schedule compression technique in PMBOK terminology - no such named technique exists.

Float (also called slack) is the amount of time a task can be delayed without affecting the project end date - it is a scheduling measurement, not a compression technique.

Crashing compresses the schedule by adding additional resources to critical path activities to shorten their duration, not by overlapping sequential activities.