Sentence Correction (SC) | In June of 1989, Princeton Township approved a developer's plans to bu

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.

Between (A) and(D)

(A) one of only eight Revolutionary War battlefields that had remained undeveloped.

"One of only eight" makes sense - The Battle of Princeton is one of limited group of battlefields. "that had remained undeveloped"
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