Answer: The correct answer is The sea kept Rome isolated from other places.
Step-by-step explanation:
During its early history Rome was isolated from other regions, and the only way to penetrate Rome was through North. That is why in couple of occasion Rome was attacked from North by the Gallic tribes. Still, it didn't destroy the country and its development.
Fishing was not such an important part of Rome's economy as people were more engaged in agriculture. Of course, sea water was not used was drinking and agriculture.