Activity D on a CPM network has predecessors B and C, and has successor F. D has duration 6. B's earliest finish is 18, while C's is 20. F's late start is 26. Which of the following is definitely true?

A) B is a critical activity.
B) C is completed before B.
C) D has no slack but is not critical.
D) D is critical and has zero slack.
E) F is critical and has zero slack.

CPM Network

Critical Path Method Network, a project management tool that models tasks and their dependencies as a network to identify key deadlines and the longest stretch of dependent activities.

Predecessors

Refers to elements or tasks that must be completed before a certain task or element can begin in scheduling and project management.

Successor

An entity or individual that follows or comes after another in a specific role, position, or sequence.