To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) The DESCRIBE DEPT statement displays the structure of the DEPT table - This option is correct. The DESCRIBE statement in SQL is used to display the structure of a table. In this case, the DESCRIBE DEPT statement will display the structure of the DEPT table.
Option B) The ROLLBACK statement frees the storage space occupied by the DEPT table - This option is incorrect. The ROLLBACK statement in SQL is used to undo the changes made in a transaction. It does not directly free the storage space occupied by a table.
Option C) The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist - This option is incorrect. Since the DEPT table is created using the CREATE TABLE statement, the DESCRIBE DEPT statement will not return an error and will display the structure of the DEPT table.
Option D) The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement - This option is incorrect. The DESCRIBE statement can be used to display the structure of a table regardless of whether there is a COMMIT or ROLLBACK statement introduced.
The correct answer is A) The DESCRIBE DEPT statement displays the structure of the DEPT table. This option is correct because the DESCRIBE statement is used to display the structure of a table, and in this case, it will display the structure of the DEPT table.