The correct answer is: C. Home, Starter, Advance Starter.
The automatic block system (ABS) is a railway signalling system that prevents trains from colliding by ensuring that only one train is in a section of track at a time. The ABS SL is a type of ABS that uses three types of signals: home, starter, and advance starter.
The home signal is the first signal that a train encounters when approaching a station. It indicates whether the train is authorized to proceed into the station. The starter signal is the next signal that a train encounters after the home signal. It indicates whether the train is authorized to proceed into the block section ahead. The advance starter signal is the last signal that a train encounters before entering a block section. It indicates whether the train is authorized to proceed into the block section ahead and whether the block section is clear.
The minimum equipment of signal in ABS SL is a home signal, a starter signal, and an advance starter signal. The home signal is used to control the entry of trains into the station. The starter signal is used to control the entry of trains into the block section ahead. The advance starter signal is used to control the entry of trains into the block section ahead and to provide warning of the next signal.
The other options are incorrect because they do not include all three types of signals required for ABS SL.