A simplifying abstraction is a concept that simplifies complex systems into more manageable and understandable terms. In the context of your options, an example of a simplifying abstraction would be operating system.
Operating systems abstract the complexities of hardware management, providing a simplified environment for users and applications to interact with the computer's resources. Other options like Microsoft Office and Photoshop are application software, while the central processing unit (CPU) is a hardware component, not an abstraction.