If selected faces do not bind a region for addition or subtraction, which command should be used?

The correct choice is the command for "Pattern Geometry." This command is used to replicate geometry in a way that allows users to create patterns of parts or features within a specified area. When selected faces do not bind a region suitable for addition or subtraction, it indicates that the geometrical relationships established by the faces are insufficient to define a closed solid or a valid surface.

Pattern Geometry allows for the distribution and repetition of geometry over a predefined set of references without needing to strictly adhere to the solid's region constraints, making it useful in cases where there are gaps or openings that would otherwise prevent operations like addition or subtraction from being successfully executed.

In contrast, the other choices focus more on specific aspects of patterning that do require the selected regions to close off or effectively define volume for operations. For example, when using commands associated with features or faces, these operations typically assume a solid or a clearly delineated area is already defined, which would not work in the case you presented where faces do not bind a region. Thus, for flexibility in replicating geometry across broader conditions, Pattern Geometry is the optimal choice.