Lag time is the

time by which an event preceded by it must be completed.

earliest time by which a successor event can follow a specific PERT event.

time performing more critical activities in parallel.

measure of the excess time & resources available.

Solution

Correct option is B

Lag time in project management refers to the delay or gap between two activities in a schedule. It is the minimum amount of time required before a successor event or activity can begin after a predecessor event or activity has been completed.
In the context of PERT (Program Evaluation and Review Technique), lag time ensures proper sequencing of dependent tasks.