DB2 administrators can utilize event monitors to gather real-time information about database activity. Event monitors capture events such as SQL statements, locks, and database changes, providing valuable insights into system performance and user behavior. This data can be used for performance tuning, troubleshooting, and auditing purposes. 

The correct option is AVG(). AVG() is used to calculate the average of a set of values. In this scenario, the DBA needs to find the average salary, which requires calculating the mean of all salaries in the department. SUM() calculates the total sum of values, COUNT() counts the number of rows, and MAX() returns the maximum value. 

The correct option is to grant SELECT permission on the specific table to the new user. This adheres to the least privilege principle, ensuring that the user only has the necessary access required for their tasks without granting unnecessary privileges. Granting ALL privileges or excessive permissions increases the risk of unintended data manipulation or security breaches. 

A scalar subquery in DB2 returns a single value and can be used within expressions or conditions in SQL statements. This makes scalar subqueries versatile and commonly used in various scenarios. 

High availability refers to the process of ensuring continuous access to data and services even in the event of a system failure. This involves measures such as redundancy, failover mechanisms, and clustering to minimize downtime and maintain uninterrupted access to critical resources. 

The WITH CONSTRAINT clause ensures that any data modification through the view meets specified criteria, such as enforcing referential integrity. 

Denormalization can lead to potential data inconsistency issues due to increased data redundancy. When redundant data is stored across multiple tables, there is a risk that updates, inserts, or deletes may result in inconsistencies if the redundant data is not properly synchronized. For instance, if a piece of redundant data is updated in one place but not in another, it can lead to inconsistencies between the related data. Thus, while denormalization can improve query performance, it requires careful management to maintain data consistency. 

JDBC (Java Database Connectivity) is a Java API that provides a set of classes and interfaces for Java applications to interact with various databases, including DB2. It allows Java applications to establish connections to DB2 databases, execute SQL queries, and process the results. JDBC provides a standardized way for Java applications to access databases, making it easier for developers to write portable database applications. By using JDBC, Java developers can leverage the features and capabilities of DB2 in their applications without needing to write platform-specific code. 

Performance tuning in DB2 aims to enhance query execution speed by optimizing various aspects such as indexes, database design, and configuration parameters to improve overall system performance. 

A Unique Constraint in DB2 ensures data integrity by enforcing uniqueness in a specific column or combination of columns, ensuring that each value in the column(s) is unique across the table. This constraint prevents duplicate entries, ensuring data accuracy and consistency. Therefore, the correct option is a Unique Constraint. Primary Key also enforces uniqueness but additionally implies uniqueness and not nullity, making Unique Constraint a more general answer for ensuring uniqueness.