According to the PMBOK® Guide, specifically within the Develop Schedule process, Resource Leveling is a schedule network analysis technique used after the initial Critical Path Method (CPM) has been performed.

Definition and Purpose: Resource leveling is a technique in which start and finish dates are adjusted based on resource constraints with the goal of balancing the demand for resources with the available supply. It is used when shared or critical required resources are only available at certain times, in limited quantities, or have been over-allocated.

The Critical Path Connection: Unlike Resource Smoothing (which does not change the critical path), Resource Leveling can often cause the original critical path to change, usually resulting in a longer project duration. It is specifically applied when " resource availability is critical. "

Key Characteristics:

It is used to address resource over-allocation.

It may result in a change (usually an extension) of the project ' s finish date.

It is a " resource optimization technique. "

Analysis of Other Options:

A. Applying calendars: Project and resource calendars are inputs to the scheduling process that define when work can occur, but they are not the analytical technique used to balance resource-constrained schedules.

C. Resource planning: This is a general term often associated with the Plan Resource Management process (identifying what is needed), rather than a specific schedule network analysis technique applied to a completed CPM.

D. Resource conflict management: This is a " Soft Skill " or " Interpersonal Skill " used to handle disagreements among team members; it is not a mathematical or technical scheduling method.