Answer: C. his four terms of office. With trees
Explanation: Option C is the best choice as it provides clear and concise information about the FDR Memorial, while maintaining proper grammar and sentence structure. It states the main feature of the memorial (representing FDR's four terms of office) and then adds additional details (trees, waterfalls, sculptures, and pools) with the use of a prepositional phrase (with trees).
Option A says "No revision is necessary," which is not a sentence describing the FDR Memorial.
Option B does not have proper punctuation and does not clearly convey the information about the memorial.
Option D does not have a proper comma after "office" and does not separate the main feature of the memorial from the additional details.