Who is credited with the invention of the telephone?

Alexander Graham Bell is credited with the invention of the telephone because he successfully demonstrated the first practical telephone in 1876. His work involved the transmission of vocal or other sounds through electrical signals, a groundbreaking achievement that transformed communication. Bell's research and experiments laid the foundation for modern telecommunications.

When considering the other figures mentioned: Thomas Edison is known for many inventions, particularly the phonograph and improvements in electric lighting, but he did not invent the telephone. Graham Watson may be a name to some, but he is not historically recognized for any significant contributions to the invention of the telephone. Leonardo da Vinci, while a brilliant inventor and thinker of the Renaissance period, lived long before the technology for the telephone existed, focusing instead on fields like art, anatomy, and engineering in a completely different era.