Which innovation 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

Alexander Graham Bell, best known for his invention of the telephone, revolutionized communication as we know it.

Explanation:

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instant communication over distance through speech

Explanation:

The telephone is a device that permits two or more persons to have an instant communication over distance through speech. It was an innovation made possible by Alexander Graham Bell. He worked at a school for the deaf and it was his focus on speech, hearing and amplification led to its invention in 1876.