The user SCOTT executes the following command successfully to increase the salary values in one of his sessions： SQL> UPDATE emp SET sal=sal*1.15 WHERE deptno=20; Before SCOTT ends the transaction， user HR who has the privileges on EMP table executes a query to fetch the salary details but finds the old salary values instead of the increased values. Why does HR still see the old data？（）
- Abecause of redo data from redo log file
- Bbecause of data from database buffer cache
- Cbecause of data from a temporary tablespace
- Dbecause of undo data from the undo tablespace