Read the passage and answer the question. 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

help fast please