Explanation:
Two-Task Common (TTC) provides this feature. Incorrect Answer:
1: SQL*Plus has nothing to do with character set and data type conversion between different character sets on the client and server.
2: Oracle Net is not responsible for this features. The Oracle Net foundation layer is responsible for establishing and maintaining the connection between the client application and database server, as well as exchanging messages between them.
4: The Oracle protocol support layer is responsible for mapping TNS functionality to industrystandard protocols used in the client/server connection.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 28-29
Chapter 2: Basic Oracle Net Architecture

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