Estimate activity resource focuses exclusively upon the identification of the number of human resources required to perform each scheduled activity

Answer: "Estimating effort, time and resources needed (and available) for scheduled activities. After Define Activities, before Develop Schedule Inputs: Activity List, Activity Attributes, Resource Calendars, Enterprise Environmental Factors Tools: Expertise, Alternatives Analysis, Published Estimating Data, Bottom-Up Estimating, Project Management Software Outputs: Activity Resource Requirements, Resource Breakdown Structure, Project Documet Updates"