Which early communication system used electrical signals sent through wires to transmit messages?

• A. Spinning Jenny
• B. Power Loom
• C. Underground Railroad
• D. Telegraph

Answer: (D)

The telegraph is an early communication system that used electrical signals sent through wires to transmit messages. An operator created pulses with a key, encoding letters in Morse code as short and long signals. These electrical bursts traveled along wires to a distant station, where they were decoded back into readable text. Relays helped boost the signal over long distances, making rapid communication across regions possible for the first time. This innovation is distinct from the other options, which relate to textile machinery or to a secret network for helping enslaved people, not transmitting messages via electrical signals. The telegraph fundamentally changed how quickly information could be shared over long distances and laid groundwork for later technologies like the telephone.