Which European country had a respectful and cooperative relationship with the Mississippians?

France

Explanation:

France, unlike other European countries settlers among the Native Americans, perceived them as allies, didn't force them to change, or took their lands and depended on them for survival in the region and particularly fur trade operations.

This in turn led the Indigenous people to performed transactions with them, specifically in exchange for European goods, the formation of military alliances, intermarry, and on few occasions converted to Christianity, and contributed politically in the administration of places such as Louisiana.

Hence, the correct answer is France

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