Why was it necessary for police officers in nineteenth-century Chicago to know Morse code?

A.) Every citizen in Chicago had a telegraph key in the home, and he or she would telegraph the nearest police office in the event of an emergency.
B.) The police officers did not need to know Morse code; only the dispatchers who telegraphed the messages to the police on the beat needed to know the code.
C.) The Chicago police department maintained signal boxes around the city with telegraph keys inside; the officer would pick up any assignments by this method.
D.) The police department in Chicago also served as the Wells Fargo telegraph station, and officers were paid to transmit telegrams during their off-duty hours.