The country that faced a unity crisis due to having a large variety of ethnic groups was D.)Austria-Hungary.
<h3>Which groups were in Austria-Hungary?</h3>
Austria-Hungary was an empire that comprised of several ethnic groups including Serbs, Bosnians, Croats, Hungarians, and Austrians.
These groups wanted independence for themselves and this led to a lot of strife in the empire.
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Native American tribes are grouped by the language they speak. For example, the Apaches are a group of several tribes that all speak the same language.
The federal legislature or congress can repeal the state laws under the necessary and proper clause in order to impose federal laws necessary to provide general welfare and common defense of the nation because they have the authority to do so. This authority was given to them because the people believed that the congress would decide for the common good.
Moreover, only the federal legislature has the right to contract debts, lay taxes and if they believed that a state law may prevent the collection of a federal tax, then they can repeal state laws making sure that it is for the benefit of the United States.
Cotton Plantations I think