The Dawes Act (1887)

The Dawes Act (1887)
Sec. 6. That upon the completion of said allotments and the patenting of the lands to said allottees, each and every member of the respective bands or tribes of Indians to whom allotments have been made shall have the benefit of and be subject to the laws, both civil and criminal, of the State or Territory in which they may reside; . . . And every Indian born within the territorial limits of the United States to whom allotments shall have been made under the provisions of this act, or under any law or treaty, and every Indian born within the territorial limits of the United States who has voluntarily taken up, within said limits, his residence separate and apart from any tribe of Indians therein, and has adopted the habits of civilized life, is hereby declared to be a citizen of the United States, and is entitled to all the rights, privileges, and immunities of such citizens, whether said Indian has been or not, by birth or otherwise, a member of any tribe of Indians within the territorial limits of the United States without in any manner affecting the right of any such Indian to tribal or other property.
-Which movement or trend was most significant in creating the conflict with the Plains Indians that ultimately led to this law?

A) railroad expansion to the West Coast
B) the extermination of the bison population throughout the Great Plains
C) the social gospel movement
D) increasing urbanization in the territories