Which of the following statements best describes the demilitarized zone (dmz) in korea?
a. north korea is the dmz; it separates china from south korea.
b. the dmz is a strip that separates north and south korea.
c. the dmz is a strip that separates korea and china.
d. the dmz is the no-fly zone over north korea.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.