Which of the following is one of the most unique elements of the Arch of Constantine?

a. It is the first use of an arch.
b. It does not glorify an Roman emperor.
c. It used previously existing sculptures from other monuments.
d. It is an early Christian monument.
e. It depicts violent scenes of battle.

c. It used previously existing sculptures from other monuments.

a. Incorrect. There were many triumphal arches in Rome when the Arch of Constantine was built.
b. Incorrect. It does glorify the Roman emperor, Constantine.
c. Correct. It does use previously existing sculptures in different styles from earlier monuments.
d. Incorrect. Though Constantine was a crucial figure in early Christianity, this monument is not a Christian one.
e. Incorrect. Though it does depict scenes of battle, earlier monuments do as well.