Prep2-10

The rise of the Incan empire rested not only on the Incas' military might and the ability of their rulers but also they imposed a highly organized economic and political system on many different ethnic groups and permitting them to retain many of their customs and often their own leaders.

(A) they imposed a highly organized economic and political system on many different ethnic groups and permitting them

(B) on their imposition of a highly organized economic and political system on many different ethnic groups, who were permitted[ 

(C) because of their imposition of a highly organized economic and political system on many different ethnic groups, who they permitted

(D) on their imposing of a highly organized economic and political system on many different ethnic groups and they permitted them

(E) imposing a highly organized economic and political system on many different ethnic groups, permitting them