Which sentence contains a redundant phrase?

What element does susan b. anthony include in this passage to strengthen her argument?

Which choice is a major detail from paragraph two? a) the great wall is a large network of several walls and towers. b) the great wall looks like a long wall snaking its way across china. c) the great wall was constructed over hundreds of years beginning in 221 b.c. d) the great wall construction encouraged several independent kingdoms to unite.

In the following conversation, which group discussion technique does emily most clearly show?