How were the civilizations of the huang river valley and the nile river valley similar?

both began around 4000 bce.
both arose in desert regions.
both failed to develop a writing system.
both were ruled by dynasties.

The civilizations of the Huang River valley and the Nile River valley were similar as both were ruled by dynasties. Option D is correct.

A dynasty is understood as a sequence of rulers from the same family, usually in the context of a feudal or monarchical system, but sometimes also appearing in elective republics.  The longest-surviving dynasty in the world is the Imperial House of Japan, otherwise known as the Yamato dynasty, whose reign is traditionally dated to 660 BC.

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he is known for discovering   the fossil of a female hominin australopithecine   known as "lucy" in the afar triangle region of hadar, ethiopia.

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