7. In multiversion concurrency control based on timestamp ordering, r1x returns the most recent version of X among all with C. write-TS(X) > TS(1). d. read TS(X) > TS(1). 8. Each leaf in a B+ tree with leaf order p-3 has the number of data pointers betweend a. 3 and 4. b. 2 and 3. c. 1and 2. d. 1 and 3.* 9. Primary or secondary indexes are not used in the implementation of the relational algebrad a. UNION operation. b. SELECT operation.4 C. JOIN operation,d d. PROJECT operation. 10. Changes applied to the database by a committed transaction should not be lost because of any failure is a desired property called a. consistency preservation. b. durability. c. atomicity.d d. isolation. 11. Covert channels are monitored with a. access control. b. data encryption. c. flow control. d. inference control. 12. Undoing write operations from the log muste a. start at the checkpoint. b. proceed in the reverse order.4 c. proceed in the forward direction. d. use the AFIM. 13. The basic two-phase locking guarantees serializability, In this protocol, each transaction a. releases no write locks until after it commits. b. acquires all locks before releasing any. c. releases no locks until after it commits. d. locks all the items before it begins.* 14. Deferred update requires a recovery procedure that ise a. UNDO/NO-REDO. b. UNDO/REDO. c. NO-UNDO/REDO.e d. NO-UNDO/NO-REDO