Which Project Time Management process includes bottom-up estimating as a tool or technique?

According to the PMBOK® Guide (Project Management Body of Knowledge), specifically within the Project Schedule Management knowledge area (historically referred to as Project Time Management):

Estimate Activity Resources (Option A): This is the process of estimating the types and quantities of material, human resources, equipment, or supplies required to perform each activity. Bottom-up estimating is a key tool and technique for this process. It involves estimating the resources for each specific activity or work package and then aggregating (rolling up) those estimates to higher levels of the Work Breakdown Structure (WBS). This is used when an activity cannot be estimated with a reasonable degree of confidence at a high level.

Estimate Activity Durations (Option C): While this process also uses various estimating techniques (Analogous, Parametric, Three-Point), the standard PMI mapping places " Bottom-up estimating " primarily as a tool for Estimate Activity Resources and Estimate Costs. For durations, the aggregation of individual activity estimates into a total is part of the scheduling logic, but the formal " Bottom-up " tool designation is most strictly associated with resources and costs.

Sequence Activities (Option B): This process focuses on identifying and documenting relationships among the project activities using the Precedence Diagramming Method (PDM). It does not involve estimating quantities or values.

Develop Schedule (Option D): This is the process of analyzing activity sequences, durations, resource requirements, and schedule constraints to create the project schedule model. It uses the outputs of the estimating processes rather than performing the bottom-up estimation itself.

In the PMI framework, Bottom-up Estimating provides the greatest level of detail and accuracy, though it is more time-consuming than top-down methods. It ensures that every component of a work package is accounted for before being summarized for the project as a whole.