Final answer:
The statement "Marc habite au Etats-Unis" is grammatically incorrect because the preposition used should be "aux" instead of "au."
Step-by-step explanation:
The statement "Marc habite au Etats-Unis" is grammatically incorrect. The correct form should be "Marc habite aux États-Unis." The use of the preposition au is incorrect because the country name États-Unis is plural in French. The correct preposition to use is aux for plural nouns.
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