The articles of confederation did all of the following
a.) serve as the first plan of government for the united states
b.) form a loose union of the states
c.) divide power among three branches of government
d.) give congress power to make war and peace

I believe it's C.) Divide power among three branches of government.
Division of powers and checks and balances was one of the reasons the Articles of Confederation was weak. 

The best and most correct answer among the choices provided by your question is the second choice or letter B.

The Articles of Confederation did all of the following except form a loose union of the states.

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