The true statements about built-in data types in Oracle are:
B: A BFILE is a data type in Oracle that allows for a read-only link to binary files stored outside the database in the operating system. This is correct as per Oracle's documentation.
D: The default length for a CHAR column, when not specified, is one character. This is according to the Oracle SQL standard.
F: A BLOB is used for storing binary data within the Oracle database, allowing for storage of large amounts of unstructured binary data.
The incorrect options are:
A: A VARCHAR2 column does not blank-pad values; it is CHAR that may blank-pad to the fixed length.
C: A CHAR column requires a length specification, although if omitted, the default is one character.
E: A VARCHAR2 column requires a length specification; without it, the statement will fail.
Reference:
Oracle Documentation on Data Types: Data Types
Oracle Documentation on LOBs: LOBs
Oracle Documentation on Character Data Types: Character Data Types