Final answer:
Chorus 1 of "Billie's Blues" consists of twelve bars, which is consistent with the traditional a. 12-bar blues form that the song follows.
Step-by-step explanation:
In the song "Billie's Blues", also known as a blues standard, we often deal with a predictable structure in the music. Traditionally, blues follow a 12-bar blues form, which means that each chorus, or complete cycle of the song, consists of twelve bars or measures. A measure is a segment of time defined by a given number of beats, grouped together for the purposes of timing and synchronization. Since each chorus in Billie's Blues is the same length, we can deduce that Chorus 1 is made up of twelve bars. This 12-bar structure is a fundamental element of blues music, and it creates the framework upon which the melody and lyrics are built.