The author mentions the movie O Brother, Where Art Thou? in the second paragraph primarily to A. encourage readers to support movies about old-time music. B. provide information about the first film to include old-time music. C. describe the influence of old-time music on Hollywood. D. explain an increase in the popularity of old-time music.

D. explain an increase in the popularity of old-time music.

Explanation:

The text speaks of old-time music, its history, and its presence in Western society.

In the second paragraph, he explains how people began to learn old-time music tunes after the popularity of the movie O Brother, Where Art Thou? which came out in 2000.

The movie uses few old songs in the soundtrack, and as it became popular, the songs became relevant again. They were played by musicians in the US and taught by schools to students, getting more covers and variants.

Therefore, his point is that the movie helped the popularity of old-time music.