Final answer:
An operating system is called real-time when it performs operations at fixed, predetermined times or within predetermined time intervals, making them suitable for applications requiring predictable response times.
Step-by-step explanation:
An operating system is real-time to the extent that it performs operations at fixed, predetermined times or within predetermined time intervals. The option (a) Real-time is the correct answer. Real-time operating systems are designed to process data and provide a response in a predictable time frame, which is a critical requirement for time-sensitive applications like embedded systems, medical equipment, and certain industrial control systems.
Their predictability differentiates them from other types of operating systems, such as multitasking or multiprocessing systems, which may not guarantee the same strict timing constraints. Unlike batch processing systems, which process batches of data or tasks at a time, often without strict time constraints, real-time systems need to follow the same path for every cycle (c), ensuring timely and deterministic behavior.