Question

Plz help me i really have to.I got a big exam to take.

Why did many cities emerge along the fall line in the southern United States?
a.
Mills powered by the fast-moving streams and waterfalls were built along the fall line.
b.
The high elevation and pleasant climate was attractive to many entrepreneurs.
c.
The color of the trees in autumn was rumored to attract tourists from all over the world.
d.
The rich foliage and soil attracted textile entrepreneurs to the area.