A. Reclaims space above and below the high-water mark without using additional space
B. Moves rows to a new physical location,resetting the high-water mark,but uses additional space during the operation
C. Deallocates space above the high-water mark that is currently not in use
D. None of the above
答案：（A）
解析：
《Adminstrator's Guide》 19.3.3