Final answer:
The option least likely to be a necessary control for the physical layout of a data processing center is Adequate physical layout space for the operating system, as this relates to software rather than the physical environment.
Step-by-step explanation:
When designing the physical layout of a data processing center, the consideration that would be least likely to be a necessary control is B) Adequate physical layout space for the operating system.
The operating system is software that does not require physical space beyond the server or computer that it's installed on. In contrast, other options such as A) Design of controls to restrict access, C) Inclusions of an adequate power supply system with surge protection, and D) Consideration of risks related to other uses of electricity in the area directly pertain to the physical setup and environment of a data processing center, addressing security, reliability, and risk mitigation associated with electrical interference and power surges.