A MCR instruction that is used with the _________ can also be used to initialize a PLC application to some predetermined state.

The First Scan Flag is the correct choice because it specifically indicates the initialization of the PLC (Programmable Logic Controller) application during its very first execution cycle after a power-on or reset event. When the PLC powers up or is reset, this flag is set to true, allowing the programmer to execute initialization routines that are crucial for establishing the desired operational state of the system. This can include setting values for variables, configuring timers, and initializing outputs or communication settings which are essential before normal operation can commence.

In contrast, options like the Last Scan Flag, Power Flag, or Control Flag do not serve this specific purpose. The Last Scan Flag indicates the final scan of a program cycle, which is useful for cleanup tasks but not for initialization. The Power Flag generally denotes the state of the power supply rather than the application state, and the Control Flag is related to specific control instructions rather than the initial setup of a program. Therefore, the First Scan Flag is uniquely suited for initializing an application state as it reflects the moment the system transitions from being inactive to fully operational for the first time.