Question 89·Hard·Standard English Conventions

Although the architectural firm promised begins a thought that can't stand alone because of Although. Where does the sentence move from the promise to the result? At the final design documents revealed, where the main part begins. The promise needs the part about the documents to complete the sentence, so we need punctuation that lets those two parts work together.

What do original limestone cornices and wrought-iron balconies add to the sentence? They name the features of the historical façade, so they're an insert, a stretch of extra information. Crossing out those details leaves the firm's promise to preserve the façade followed by the news in the design documents. The words still make a complete sentence once we use the normal comma between the opening Although part and the main part.

The punctuation in balconies—the final design documents revealed shows where the description ends and the main part starts. Could the blank instead mark a break between complete sentences? The words before the blank can't stand alone, because Although makes them depend on the later part about the documents. A colon needs a complete sentence before it, and a semicolon needs one on each side, so the colon and semicolon versions don't work.

A dash closes the insert at balconies—the, so a dash must open it. The version façade, the would mix a comma with a dash, while façade—the gives a matching pair. The closing dash also separates the opening Although part from the main part, so we don't add a comma beside it. Choice C.