According to the PMBOK® Guide and the Standard for Project Management, effective communication is a critical pillar of project success, especially when a formal leadership structure (like a dedicated project manager) is missing.

The three primary communication methods recognized by PMI are Interactive, Push, and Pull. In the scenario described:

Interactive Communication: This method involves a multidimensional exchange of information in real-time. It includes meetings, phone calls, video conferencing, and instant messaging. It is the most effective way to ensure a common understanding among all participants on a given topic. Because the team lacks a project manager to coordinate activities, the functional manager must ensure that the delegation is fully understood, expectations are clear, and the team can provide immediate feedback or ask clarifying questions.

Comparison with other options:

Push Communication: This involves sending information to specific recipients who need to know it (e.g., emails, memos, reports). While this ensures the information is distributed, it does not guarantee that it reached or was understood by the intended audience. Without a PM to follow up, " Push " communication risks leaving the team misaligned.

Verbal/Oral Communication: These are types of communication, but they are not categorized as " methods " in the same way Interactive, Push, and Pull are in the Communication Management Plan. Furthermore, " Verbal " and " Oral " are often used interchangeably in general conversation, but in a PMI context, Interactive is the formal method that encompasses these while focusing on the bidirectional flow of information.

In a self-managing team environment (or one where the PM role is absent), Interactive communication is essential to resolve conflicts, foster collaboration, and verify that the project ' s strategic objectives are correctly interpreted by the team members.