Hiram rhodes revels was a key figure during the reconstruction era because a) he was a co-founder of the ku klux klan. b) he to dismantle the early formation of the ku klux klan. c) he was the chief prosecutor in the impeachment trial of andrew johnson. d) he was the first african-american elected to a seat in the u. s. congress.

The correct answer is option D) "he was the first African-American elected to a seat in the U.S. Congress". Hiram Rhodes Revels was a Republican U.S. Senator and from this position, the first African-American to serve in Congress. Rhodes Revels was also a minister in the African Methodist Episcopal Church, and he born and died as a freeman.