The correct answer is D. The audience knows the boastful king's power did not last.
Explanation
Dramatic irony is a literary device that is based on giving the reader information about the story so that he understands the hidden meanings of the story related to the actions of the characters. In addition, the reader understands aspects that the characters themselves are unaware of, creating a feeling of suspense. In the excerpt presented the narrator tells the reader the power of the king will not last, as the narrator says "My name is Ozymandias, king of kings: Look on my works, ye Mighty, and despair!" Nothing beside remains".
According to the above, it can be established that the correct answer is D. The audience knows the boastful king's power did not last.