Which statements describe how china's early civilization differed from other river valley civilizations?
choose all answers that are correct.
a.
it was the only civilization to develop trade with its neighbors.
b.
natural barriers isolated china from neighboring civilizations.
c.
the ancient chinese failed to develop any kind of writing.
d.
china's civilization is the oldest continuous civilization in the world.
e.
in other river valley civilizations, power was in the hands of a single ruler.