The project's contingency allowance is a provision in the project budget that is intended to cover known risks that may affect the project costs. The risk of increased fuel costs was identified and included in the contingency allowance, so the project manager should use it to process the freight invoices at the actual shipping costs. This is the best way to handle the risk without affecting the project scope, schedule, or quality.
Requesting a formal change order from the customer (option B) is not necessary, as the project budget already has a provision for this risk. Processing the freight invoices for the budgeted amount and hoping the shipping company will forgive the difference (option C) is unethical and unprofessional, as it violates the terms of the contract and the PMI Code of Ethics and Professional Conduct. Asking the project sponsor to cover the additional shipping costs on the company's reserves account (option D) is also not appropriate, as the company's reserves are meant for unknown risks that are beyond the project's control, not for known risks that are already accounted for in the project budget. References: PMI, The Standard for Risk Management in Portfolios, Programs, and Projects, 2019, p. 72; PMI, A Guide to the Project Management Body of Knowledge (PMBOK Guide), 6th ed., 2017, p. 252.
The project manager should use the contingency allowance to cover the additional shipping costs, as it was specifically included in the project budget for such risks. This approach avoids requesting unnecessary changes or relying on external sources to cover the cost overrun.