If I am convinced that my own neighborhood is safer than it used to be, but that the crime rate in my society is at an all-time high, I am falling victim to... A) Probability neglect
B) Shifting the burden of proof fallacy
C) Presumptive pessimism

the answer is a

Explanation:

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.