So I definitely got that question wrong because I lost focus and picked producer because I didn't know what an arranger did (and, yes, I completely realize the definitions were irrelavent to TCR).
Anyways, I am currently studying for a final in my music class and what two definitions do I come across in the 'jazz' section?
PRODUCER AND ARRANGER!!!
I think of it as the good lord throwing salt on my LSAT wounds, but at least I know that Duke Ellington was an especially good composer and arranger.