Monumental Entrances to Roman Provincial Towns, Such as the Porta

Monumental entrances to Roman provincial towns, such as the Porta Palatina at Turin, served all of the following functions EXCEPT

A) blocking wheeled traffic from entering the town.
B) announcing the presence of Roman rule and Roman arms in the provinces.
C) permitting local officials to regulate traffic entering or leaving the town.
D) providing for defense in the event of an attack.