Which of the following is true about the great wall of china? select one: a. while it was actually built over many dynasties, to keep out invaders, the greatest construction began during the qin dynasty. b. along with the great pyramids and the colossus of rhoades, the great wall was considered by europeans to be one of the “seven wonders” of the ancient world. c. the wall was built to keep european invaders out during china’s feudal times. d. the wall saw its greatest expansion during the xia and shang dynasties