During the nineteenth century, “prelude,” “impromptu,” and “intermezzo” were common titles for:

In the nineteenth century, the titles “prelude,” “impromptu,” and “intermezzo” were mutual titles for short, lyric piano pieces at that time. Prelude normally features a small amount of rhythmic and melodic themes that reappear through the piece. While the impromptu, is a freestyle musical work with the personality of an unrehearsed improvisation like it was driven by the essence of the moment, usually done in a piano. Lastly, intermezzo is a work which fits among other musical or dramatic individuals, such as acts of a play or actions of a larger musical work.

b: the establishment clause  

b: socialism  

sonar maybe? ? i dont know the choices