According to the PMBOK Guide, the project manager should communicate the organizational culture and project goal to the external stakeholders in a formal and written manner. This will help the stakeholders understand the context, scope, objectives, and deliverables of the project, as well as the roles and responsibilities of the project team and other stakeholders. A report is an appropriate communication tool for this purpose, as it can provide a comprehensive and structured overview of the project information. The other options are either too informal, indirect, or ineffective for communicating the organizational culture and project goal to the external stakeholders. References: PMBOK Guide, 6th edition, page 376-377, section 10.1.2.1.