Explanation:
If the table doesn’t exist in your schema, you must prefix the table name with the schema information, separating the owner from the table name with a period.
Incorrect Answers:
1: If you don’t have DEPT table in your schema, this statement will fail.
3: This statement is incorrect.
4: This statement is incorrect. ALL_USERS view is used to extract information about users.
OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 28-29
Chapter 1: Overview of Oracle Databases

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