Melody ......................................................
Answer: 20th century there was a large increase in the variety of music that people had access to,Sound recording was also a major influence on the development of popular music genres, because it enabled recordings of songs and bands to be inexpensively and widely distributed nationwide or even, for some artists, worldwide.
for more ex go here
https://www.classicfm.com/discover-music/periods-genres/modern/
I think the answer is a and b
