To determine the MOST likely estimate for the length of project activities, a project manager would use which of the following?

PERT (Program Evaluation and Review Technique) is a method used for activity duration estimation that considers three points (optimistic, pessimistic, and most likely) to calculate a weighted average, providing a more realistic and statistically derived "most likely estimate" for activity length, accounting for inherent uncertainties. This approach helps in producing a more accurate and reliable schedule baseline.

A Gantt chart is a scheduling tool that visually represents project tasks and their dependencies over time, but it does not calculate activity duration estimates itself.

A WBS Dictionary provides detailed information about Work Breakdown Structure (WBS) elements but does not calculate activity duration estimates.

SPI (Schedule Performance Index) is an Earned Value Management metric used to measure schedule efficiency and evaluate project performance, not to determine activity duration estimates.