The correct answer is: A. Through
A long short long short whistle means that the train is going through the station without stopping. The home signal is a red light that indicates that the train is not allowed to proceed. When the loco pilot sounds the whistle, it is a signal to the stationmaster that the train is going through and that the home signal can be cleared.
The other options are incorrect because they do not accurately describe the situation. Option B, “Train parted,” means that the train has stopped at the station and passengers have gotten on or off. Option C, “Received train,” means that the train has arrived at the station and is being unloaded. Option D, “None of these,” is incorrect because it does not list any of the possible meanings of the whistle.