Which invention is Thomas Edison credited with developing?

• A. Phonograph
• B. Transcontinental Railroad
• C. Standard Oil Company
• D. Carnegie Steel Company

Answer: (A)

Thomas Edison is credited with developing the phonograph, which was the first device capable of recording and reproducing sound. Invented in 1877, the phonograph marked a significant advancement in audio technology and played a crucial role in the music industry. It allowed for the recording of voices and music, making audio playback accessible for the first time. This innovation not only transformed entertainment but also had lasting impacts on communication and media.

The other options provided relate to prominent figures and developments of the time but are not associated with Edison. The transcontinental railroad was completed in 1869 and is attributed to multiple individuals and companies working together to connect the east and west coasts of the United States. The Standard Oil Company, founded by John D. Rockefeller, became a dominant force in the oil industry, while the Carnegie Steel Company, established by Andrew Carnegie, revolutionized steel manufacturing processes. Each of these contributions was significant in shaping American industry and infrastructure, but they are not inventions created by Thomas Edison.