Final answer:
The sentence in question contains an error in section C, with a missing comma and incorrect word placement. The correct sentence is: 'Alaska, the northernmost state in America, is the country's largest.'
Step-by-step explanation:
The sentence in question is: Alaska the northernmost state America, is the country's largest.
The error in this sentence is in section C. The sentence should read: Alaska, the northernmost state in America, is the country's largest. The error is the missing comma after 'Alaska' and the incorrect placement of 'America' in the sentence. The corrected sentence provides clarity and proper grammar.