The author's primary purpose is to

Hi There, I was down to Option (D) and Option (E), and I ultimately chose (D) because the focus of the passage seemed to me to be more addressing why those who disapprove of the USSC's decisions regarding Native Americans are wrong (i.e. the "disputants"). More generally, can you offer any advice for timely resolution between alternatives when you get down to two choices that both sound good? Thanks!