How did people use a telegraph to communicate without speech? with a series of bellelgi varying pitches
with words typed out on a typewriter
with Morse code
with overland mail carriages

"with Morse code".

Morse code is a technique for transmitting content data as a progression of on-off tones, lights, or snaps that can be straightforwardly comprehended by a learned audience or onlooker without special gear. It is named for Samuel F. B. Morse. Every Morse code sign speaks to either a content character (letter or numeral) or a prosign and is spoken to by a distinct sequence of dabs and dashes.

Explanation:

c) the invasion of the shang