Explanation:
When a checkpoint occurs, Oracle must update the headers of all data files to record the details of the checkpoint. At specific times, all modified database buffers in the SGA are written to the data files by DBWn. This event is called a checkpoint. The checkpoint process is responsible for signaling DBWn at checkpoints and updating all the data files and control files of the database to indicate the most recent checkpoint. Incorrect Answer:
4: The checkpoint does not affect the parameter files.
5: The checkpoint does not affect the archive log files.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 28-29
Chapter 2: Basic Oracle Net Architecture

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