The Romans were descended from a cluster of peoples who had crossed the Alps into Italy during the second millenium B.C. and spoke a variety of Indo-European dialects. Recent archaeological research has pushed the origins of the city of Rome back to at least the tenth century B.C., several centuries earlier than the traditional date 753 B.C., which the Romans themselves considered their citys foundation year. Romes strategic location along the Tiber River brought it many different advantages. Trading ships could navigate the Tiber as far as Rome, but no farther; the city could thus serve as a port without being threatened by attack from the sea. Romes famous hills increased the defensibility of the site. In other words, as a city, Rome was situated at a junction across the Tiber, making it a major land and river crossroads.
According to the passage, Rome was founded at a site along the Tiber, which ----.
A) was vulnerable to attacks from the hills around
B) provided a perfect crossing across the river
C) had been a major trading centre even before the tenth century B.C.
D) enabled merchant ships to sail far into the country
E) was most exposed to the dangers from the sea