Explain briefly why interrupts are indispensable in a single-processor system that supports parallel activities?

Interrupts are indispensable in a single-processor system that supports parallel activities because they allow the CPU to respond promptly to external events and prioritize tasks efficiently. Without interrupts, the CPU would have to continuously poll each task, wasting valuable processing time and leading to delays in responding to critical events. Interrupts enable the system to switch context rapidly between tasks, ensuring that high-priority processes receive the attention they need while still allowing for multitasking. This mechanism enhances responsiveness and resource utilization in a single-processor environment.