Question #N588

The author of a new book about the history of New York City’s subway system, writes that, "The subway system was a marvel of engineering, and the result of a massive amount of planning and labor, it is a testament to the vision of those who designed and built it."

Which choice best revises the sentence so that it conforms to the conventions of Standard English?
A. The subway system was a marvel of engineering, and the result of a massive amount of planning and labor, and it is a testament to the vision of those who designed and built it.
B. The subway system, a marvel of engineering, and the result of a massive amount of planning and labor, is a testament to the vision of those who designed and built it.
C. The subway system was a marvel of engineering, the result of a massive amount of planning and labor; it is a testament to the vision of those who designed and built it.
D. The subway system was a marvel of engineering and the result of a massive amount of planning and labor, it is a testament to the vision of those who designed and built it.