How did the Mongols use siege warfare in their conquests? by sailing up to a coastal city and firing cannons at it for many days
O by surrounding a city and preventing anything from getting in or out
O by sending so many troops into battle that the enemy was outnumbered
O by setting up points on hilltops where the enemy's movements could be watched

its b) by surrounding a city and preventing anything from getting in or out

Explanation:

i took the unit test review good luck

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.