the cause for this is that the startup disk is now not available or doesn't contain a working Mac operating system.
The hard disk is used in the system to boot the operating system.
it contains the main computing software. In Mac system, the startup disc involves the system software i.e. MacOS system software.
Operating system is the main system or the software in every computer system that is responsible for performing and supporting each and every basic function in the computer such as controlling peripherals, scheduling tasks etc
to know more about Mac operating sytem, visit
https://brainly.com/question/28465993
#SPJ4
