Free PMI Project Management Professional (PMP) Practice Question

The correct answer is 12. The Early Start (ES) of an activity is determined by the latest Early Finish (EF) of its predecessors. In this case, Activity B has two predecessors: Activity A with an EF of 10, and Activity C with an EF of 12. Since we need to wait for both predecessors to finish before starting Activity B, we must use the later of the two EF values, which is 12. This ensures that all predecessor activities are completed before Activity B can begin. It's important to note that we don't add these values or use the earlier EF, as either approach would lead to an incorrect schedule.