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Which of these sentences uses correct capitalization?
Did you know that a Swedish engineer designed the Monitor, an Ironclad ship in the Civil War?

Did you know that a Swedish engineer designed the Monitor, an ironclad ship in the Civil war?

Did you know that a Swedish Engineer designed the Monitor, an ironclad ship in the Civil War?

Did you know that a Swedish engineer designed the Monitor, an ironclad ship in the Civil War?