The Rhine has served as a link between southern and northern Europe since prehistoric times, enabling trade and cultural exchange, which in turn led to the establishment of settlements within a small geographical area. Which statement best analyzes the effects of conditions described in this passage?

a
The cultures of these areas developed independently
b
Early settlements combined to form a chain of villages and small towns
c
This encouraged agricultural development among early settlers
d
Close communities caused groups to go to war with one another for resources