The phrase "Jazz is the greatest American musical form" is what kind of clause?

Jazz is the greatest American musical form, and Duke Ellington is its greatest genius.]]> The phrase "and Duke Ellington is its greatest genius" is what kind of clause?

Jazz is the greatest American musical form, and Duke Ellington is its greatest genius.]]> This sentence is:

Jazz is the greatest American musical form, and Duke Ellington is its greatest genius.]]> Pronounce the sentence.

Jazz is the greatest American musical form, and Duke Ellington is its greatest genius.]]>