What are the elements of communication? Describe them briefly?

What is the narrators main conflict in this passage

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.

How do headings organize your information?