Final answer:
The correct command to delete the row for the Free Bookmark from the PROMOTION table is: DELETE FROM PROMOTION WHERE Promotion_Name='Free Bookmark'; as it's syntactically correct and targets the desired row.
Step-by-step explanation:
Based on the contents of the PROMOTION table, to delete only the row for the Free Bookmark from the table, the correct SQL command to use is option a): DELETE FROM PROMOTION WHERE Promotion_Name='Free Bookmark';.
This command will search the PROMOTION table for a row where the column Promotion_Name matches the value 'Free Bookmark' and will delete that specific row. The other options provided are syntactically incorrect or are not valid SQL commands for deleting rows.