The correct option is D Sara looked at him and said, "I will be back in five minutes!''
Let’s examine the sentence: “Sara looked at him and said, I will be back in five minutes!” The sentence is in direct speech. In direct speech, the actual words (with no change) of speaker are quoted. The exact words (or actual words) of the speaker are enclosed in double inverted commas or quotation marks. So, the correct way to present this sentence is, ‘Sara looked at him and said, “I will be back in five minutes!”’ Hence, Option D is the correct answer.