648.Note the following statements that use flashback technology: 1. FLASHBACK TABLE TO SCN ; 2. SELECT * FROM AS OF SCN 123456; 3. FLASHBACK TABLE TO BEFORE DROP; 4. FLASHBACK DATABASE TO TIMESTAMP ; 5. SELECT * FROM VERSIONS AS OF SCN 123456 AND 123999; Which of these statements will be dependent on the availability of relevant undo data in the undo segment?
A.1, 2, and 5
B.1, 3, and 4
C.2, 3, 4, and 5
D.1, 2, 3, 4, and 5
正确答案是A