What musical genre does Copland use to highlight the frontier themes in Billy the Kid and Rodeo?

A. Square dance songs

B. Fiddle music

C. Hymns

D. Cowboy songs

I believe the correct answer is D. Cowboy songs.

Aaron Copland, American composer, used cowboy songs to highlight the frontier themes in his ballets "Billy the Kid" and "Rodeo". Since Copland’s most important ballets are based on American folk material (Billy the Kid (1938), Rodeo (1942), and Appalachian Spring (1944)), he used cowboy songs and American folk songs to contribute to the main themes.

The answer is cowboy song ...