If the Solar System were the size of the room, how big would the Earth be? The size of the disk in her hand
The size of the globe next to her
The size of a microscopic bacteria not visible to the human eye - ANSWER

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.

the answer to your question is,

d. when a child was born.

-mabel < 3