Which of the following features could be included in an ideal functional diagram?

An ideal functional diagram serves to illustrate the relationships and connections between different functional areas within a project, highlighting how those areas interrelate and flow together. This approach emphasizes the functionality and circulation patterns that will occur in the space. By mapping out these connections, planners and designers can better understand the operational requirements and ensure that each area is efficiently integrated into the overall design.

In contrast, including exact measurements of space, designing structures, or selecting materials relates more to detailed architectural plans and specifications rather than the overarching functional relationships that a functional diagram typically represents. The functional diagram's primary purpose is to convey concepts rather than to delve into the specifics of dimensions, material choices, or structural details. Thus, focusing on the connections between different functional areas captures the essence of what such a diagram should convey, making it the correct choice.