Warner's study of the city of Natchez in the American Deep South showed that the 'colour line' there was:
(A)no longer a powerful influence upon race relations (B)a way of marking out the land so that black people had less space for housing (C)a new policy that had been introduced to assimilate black and white groups (D)a sharp division between black and white castes, underpinned by beliefs about white superiority
D