Explanation:
There is only one SQL*Plus command in this list: DESCRIBE. It cannot be used as SQL command. This command returns a description of tablename, including all columns in that table, the datatype for each column, and an indication of whether the column permits storage of NULL values.
Incorrect Answers:
1: INSERT is not a SQL*Plus command. It’s data-manipulation language (DML) command.
2: UPDATE is not a SQL*Plus command. It’s data-manipulation language (DML) command.
3: SELECT is not a SQL*Plus command.
5: DELETE is not a SQL*Plus command. It’s data-manipulation language (DML) command.
6: RENAME is not a SQL*Plus command.
OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 43
Chapter 1: Overview of Oracle Databases

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