When a change (such as a new regulatory requirement) is introduced, the first step is always to assess the potential impact. This allows the project manager to understand how scope, schedule, cost, or quality may be affected. Only after assessing the impact should changes be formally documented and implemented.

The PMBOK® Guide – Seventh Edition emphasizes adaptive planning and impact assessment in response to external change (e.g., legal or regulatory). The guide states: "Assess changes to determine impact before recommending a course of action."

Option A (Increase slack) is reactive and premature without assessment.

Option B implies implementation before assessing consequences.

Option C (Consult the plan) might follow, but impact assessment is the most immediate and necessary action.