Final answer:
The statement that there is only one operating system available for all computers is NOT true. Multiple operating systems exist, catering to various requirements, and they serve as a mediator between application software and hardware.
Step-by-step explanation:
The correct answer to the question of which statement is NOT true about an operating system is: d. There is only one operating system available for all computers. This statement is false because there are multiple operating systems available for computers, each with its own features and designed to meet different needs. The operating system (OS) acts as a mediator between the application software and the hardware, coordinating all the activities and ensuring that instructions are executed efficiently.
Although early mainframes and personal computers had OSs tightly controlled by manufacturers and a few software businesses, the landscape has evolved, with many different operating systems now available, ranging from proprietary systems such as Windows and macOS to open-source variants like Linux and its various distributions.