Final answer:
Music at the turn of the 20th century was primarily provided by live bands and phonograph records, with radio broadcasting not becoming prevalent until the 1920s. The correct options are a and d.
Step-by-step explanation:
At the turn of the 20th century, music was primarily provided by live bands and phonograph records. The invention of the phonograph by Thomas Edison in 1877 allowed people to record and play back sound, leading to its use for entertainment and the eventual creation of audiovisual presentations.
Although radio wave technology was pioneered in the late 1800s, it wasn't until the 1920s that radio broadcasting began in earnest, becoming a major source of entertainment and news, greatly shaping a mass culture.
Hence, Options a and d are correct.