Which sentence corrects the punctuation errors in the following dialogue: "Was it Gwendolyn Brooks," Shawna asked, "who wrote the poem "Ode on a Grecian Urn"?"

The correct option provides the appropriate punctuation and capitalization needed to properly structure the dialogue. In this case, the first part of the dialogue is a direct question, which should end with a question mark. However, the entire sentence is part of a broader quotation that attributes the question to Shawna; therefore, it needs to maintain the clarity of both the question and the dialogue structure.

In the response, the questioning part of the dialogue, "Was it Gwendolyn Brooks," is correctly enclosed within quotation marks, indicating that it is speech. However, an important aspect here is accurately punctuating the end of the question, which has been done properly by including a question mark before the closing quotation mark—signifying that the sentence is indeed a question.

Additionally, attributing the dialogue using “Shawna asked” is correctly done to present who is speaking but requires a comma following the first quoted portion. The distinction between direct quotations and the speaker's attribution is essential to maintain the flow and clarity of the conversation. Therefore, the choice correctly addresses these grammatical and punctuation rules, leading to a well-formed sentence.