Which quotation is punctuated correctly?

In American English, a comma introducing a direct quotation goes inside the quotation marks, and a sentence-ending period also goes inside them. Choice D correctly punctuates the quotation: According to President Roosevelt, “The world was at the brink of war.” In A and B, the period is outside the closing quotation mark, and C is missing a comma before the quotation.

AI-written and checked against the verified answer.