Question

which of these innovations was made possible by alexander graham bell?
instant communication through the written word
instant communication between trains
instant communication through speech
instant communication using a special code

Explanation:

Alexander Graham Bell is known for inventing the telephone, which enables instant communication through speech. The other options: instant communication through the written word is related to writing systems or telegraph (but not Bell's main innovation), instant communication between trains is not his work, and instant communication using a special code is like Morse code (not Bell's).

Answer:

C. instant communication through speech