Explanation:

- Option 1: Network Maintenance

- Involves managing network hardware, communication, and connectivity.

- This is usually handled by Network Administrators, not DBAs.

- Not a core function of DBA.

- Option 2: Routine Maintenance

- Includes tasks like backup, recovery, performance monitoring, etc.

- This is a key responsibility of a DBA.

- Option 3: Schema Definition

- Involves defining tables, fields, relationships, and structure.

- DBAs are responsible for this work.

- Option 4: Authorization for Data Access

- Involves controlling who can view or modify data within the database.

- Granting and restricting permissions is a core DBA function.