To avoid resource constraints, the PMO professional should engage with key stakeholders early during planning to assess and secure necessary resources. PMI-PMOCP emphasizes stakeholder involvement to identify realistic resource availability, negotiate commitments, and align expectations.

Inviting executives to engage (option A) or including management reserves (option C) may help but do not replace upfront stakeholder collaboration. Assessing past plans (option D) provides data but lacks stakeholder negotiation, which is critical for resource allocation.