Another way that roman road building led to expansion besides trade was that it

allowed for the creation of unique architectural styles.
led to a uniform law system.
allowed the military to move people and supplies further.
created less class divisions due to economic expansion.

It allowed the military to move people and supplies further.

Explanation:

The building of the roads in the Roman empire secured them during the ancient times. Besides being used for trading, it also allowed the military to move people and supplies further. The roads were primarily built in a way that the Roman military would strategically win from their enemies. It allowed them to respond swiftly to intruders and also helped ease the distribution of supplies in the empire.

Besides these reasons, it was also built to help protect the empire from thieves. They were also well-patrolled, so travelers could also ask any assistance when they're lost.

Thus, this explains the answer.

c. have a great day ~ma.tiah

the answers are a b and d