A functional team is best suited for relatively simple product line extensions or improvements. Functional teams consist of members from the same department or function who bring specialized skills and knowledge to the project. These teams are effective for projects that do not require extensive cross-disciplinary collaboration and can be managed within a single functional area. For highly complex projects or those requiring innovation across multiple disciplines, a cross-functional or project-specific team would be more appropriate. Reference: "Project Management: A Systems Approach to Planning, Scheduling, and Controlling" by Harold Kerzner explains the suitability of different types of teams for various project complexities.