Two of the cultural similarities of early river valley civilizations were select all that apply.

reduction in the amount of food needed
forming of organized government as population increased
overpopulation, causing people to move from urban setting to rural one
conversion of more land to productive fields

Explanation:

Since the river valley civilizations were based around rivers, they developed a system of government called Hydraulic Empires. The Hydraulic Empires are a social government structure that maintains power through exclusive control over water access. 

This means that the government developed a bureaucracy and central coordination that controlled the floods and the irrigation that was provided by the rivers.

This is also directly linked to the conversion of more land to productive fields because the food surplus was what made possible the development of these river valley civilizations and when more food was being produced under these Hydraulic Empires, more power for them.

i believe the correct answer is option b. most eastern european nations joined nato.

though i could be wrong, option d. the eastern european nations were granted complete independence, would be another choice.

hope this ! : )

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