语法新东方OLD BOOK section11

23. In June of 1989, Princeton
                        Township approved a

developer's plans to build 300 houses on a large

portion of the 210-acre site of the Battle of Princeton,

one of only eight Revolutionary War battlefields

that had remained undeveloped.

(A) one of only eight Revolutionary War

battlefields that had remained undeveloped.

(B) one of eight of the only Revolutionary War

battlefields that have remained undeveloped

(C) one of the only eight undeveloped Revolutionary

War battlefields that remains

(D) only one of eight Revolutionary War

battlefields to remain undeveloped

(E) only one of the eight remaining undeveloped

Revolutionary War battlefields

key是A。在这里only eight表示强调吗？