Visual Explain in DB2 aids in query optimization by providing a visual representation of the access paths chosen by the query optimizer for executing the SQL statement. This helps in understanding and analyzing the query execution plan, which is crucial for optimizing query performance. 

The INSERT command in SQL is used to add new records (rows) to a table. It allows users to specify the values for each column in the table when inserting new data. This command is essential for adding data to tables and expanding the dataset in a database. 

The IMPORT utility in DB2 supports various common file formats such as CSV (Comma-Separated Values), fixed-width, and XML files. These formats are widely used for data interchange and are compatible with many external systems and applications. Using the IMPORT utility, users can efficiently load data from these file formats into DB2 tables, facilitating seamless integration and data exchange between different systems. 

The DB2 Command Line Processor (CLP) provides a set of built-in commands that allow administrators to perform common administrative tasks programmatically, enabling automation. By leveraging scripting languages such as Bash or PowerShell, administrators can create scripts to automate routine database maintenance, backup and recovery operations, and performance monitoring tasks. This automation reduces manual effort, minimizes the risk of errors, and improves overall operational efficiency. 

To verify the successful completion of the DB2 installation process, you can check for the db2setup.log file in the installation directory. This log file contains detailed information about the installation process, including any errors encountered. Checking this log ensures that the installation completed without issues. 

Tags in DB2 serve the purpose of labeling and organizing database objects. They allow users to categorize and manage objects more efficiently, facilitating better organization and management of database resources. For example, tags can be used to group tables, views, or stored procedures that belong to a specific project or department. 

Denormalization can lead to reduced query execution time as it reduces the need for complex joins and enables faster data retrieval. This can improve overall system performance and response times. 

The DECLARE CURSOR statement is used to declare a cursor in DB2. This statement defines the result set for the cursor, specifying the SELECT statement that will be used to retrieve rows. Once declared, the cursor can be opened, fetched, and closed to process the rows returned by the associated query. 

The correct option is 'ORDER BY'. This clause is used to sort the result set returned by the SELECT statement in either ascending or descending order based on one or more columns. It helps the developer to retrieve records in a specific order as required. 

The correct option is to review database logs to identify the source and nature of unauthorized access attempts. Database logs often contain valuable information about login attempts, failed authentication, and suspicious activities, which can help the DBA understand the scope of the security breach and take appropriate actions to mitigate risks. Implementing two-factor authentication, temporarily disabling access, or enhancing firewall restrictions are valid security measures but may not directly address the ongoing security breach.