(05.04 mc)which of these is true of the roman road system?
augustus had all roman roads paved with marble.
improving the roads the roman empire to grow.
the road system provided easy access for enemies to invade rome.
roman roads were built only during times of peace.

The correct answer is D) Roman roads were built only in times of peace.

The statement that is true of the Roman Road system is "Roman roads were built only in times of peace."

In those years of the Roman Empire, the Roman army needed good roads for the transportation of soldiers, weapons, supplies, and goods. Roman engineers used the technique called "Goma" to build roads in stretched places. They dug ditches on both sides of the road that served as drains. The collected rock from the area and put them in layers until were heavy enough for the heavy Roman carts. The thing with the Roman roads is that the roads were only built in times of peace.  

the answer is a) high entry costs