Final answer:
When the file system contains more than one bootable partition, the boot loader will search each partition for the kernel and run the first one it finds. The system administrator does not need to manually select the operating system to be booted.
Step-by-step explanation:
When the file system contains more than one bootable partition, a boot loader is parallel searching each partition for the kernel and runs the first one it finds. The boot loader is responsible for loading the operating system's kernel into memory and starting the boot process. It scans each bootable partition for a valid kernel and executes the first one it encounters.
For example, let's say there are two bootable partitions: Partition A contains the kernel for Operating System X, and Partition B contains the kernel for Operating System Y. The boot loader will search both partitions, and if it finds the kernel for OS X first, it will run OS X. If it finds the kernel for OS Y first, it will run OS Y.
The system administrator (admin user) does not need to manually select which operating system will be booted in this scenario.