A PERT chart (Program Evaluation and Review Technique) is the best tool here because it supports planning work by modeling task durations and dependencies and is commonly used to analyze uncertain activity durations. In CompTIA Project+ objectives, schedule development includes identifying dependencies and estimating durations; PERT is a classic planning technique used to represent activities, relationships, and time estimates to build a logical schedule network.
A Gantt chart is excellent for visualizing the schedule on a calendar timeline once activities and dependencies are defined, but the question emphasizes planning activities: mapping scope into tasks, calculating durations, and identifying dependency logic-work that PERT/network analysis directly supports. A milestone chart is higher-level and won't show detailed dependencies or duration calculations. A velocity chart is an Agile metric for throughput across iterations; it does not map full scope with dependency logic for a predictive schedule plan.
Therefore, for planning that combines scope decomposition, duration estimation, and dependency identification-especially where time estimates may be refined-the best choice is the PERT chart, which helps the PM understand sequencing, critical paths, and schedule risk before presenting the final schedule view.