Examine the command： ALTER DATABASE ADD SUPPLEMENTAL LOG DATA （PRIMARY KEY） COLUMNS； What does the command accomplish？（）
A. Creates an additional copy of the database online redo log files.
B. Stores the primary key column values of each row involved in a DML operation in the online redo log files.
C. Stores the primary key column values of each row involved in a DML operation in the supplemental log files.
D. Stores the old and new primary key column values of each row involved in a DML operation only when the primary key is modified in the online redo log files.
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