Why was the qin dynasty significant? a. qin shi huangdi unified china, completed the construction of the great wall, repaired the war damage, and extended the canal system. b. qin shi huangdi could not unify china, but he completed the construction of the great wall, repaired the war damage, and extended the canal system. c. qin shi huangdi unified china, began the construction of the great wall, repaired the war damage, and extended the canal system. d. qin shi huangdi could not unify china, but he began the construction of the great wall, repaired the war damage, and extended the canal system.