【单选题】
The user SCOTT executes the following command successfully to increase the salary values in one of his sessions： <br /> SQL> UPDATE emp SET sal=sal*1.15 WHERE deptno=20; <br /> 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. <br /> Why does HR still see the old data？（）
A、because of redo data from redo log file
B、because of data from database buffer cache
C、because of data from a temporary tablespace
D、because of undo data from the undo tablespace
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