※This sample exam is different from those that appear in the actual OSS-DB Exam.
The information schema is organized as a collection of views in a schema called information_schema that provides various information about the objects in the database.
Since it is defined in the SQL standard, it is portable, and other RDBMS can acquire information with the same SQL, but it is not available in all RDBMS.
Because it conforms to the standard, information on proprietary extensions of PostgreSQL are not included in the information schema. For extended functions, you can inquire by using the system catalog.
Therefore the correct answers are B and C.