In DB2, the component that defines the name of the database object within a tag is known as the tag identifier. This identifier uniquely identifies the object associated with the tag and allows users to reference and manipulate it within the database environment. For instance, when creating a tag for a table, the tag identifier would typically specify the name of the table. 

Multi-dimensional clustering (MDC) in DB2 offers advantages such as improved query performance due to reduced I/O, better space utilization, and enhanced data distribution. By organizing data into multiple dimensions, MDC optimizes query processing by grouping similar data together, which leads to reduced I/O and improved performance. Additionally, MDC can help in achieving better space utilization by storing related data together, resulting in more efficient storage allocation. 

Visual Explain in DB2 helps identify factors related to query performance tuning, such as index selection. By visualizing the access paths chosen by the query optimizer, it becomes easier to evaluate the effectiveness of indexes and make informed decisions to improve query performance. 

Application Processors handle user requests and interact with the database manager. They manage incoming queries, execute them, and communicate with other components of the DB2 system as necessary. 

Rectangles in an Entity-Relationship Diagram (ERD) represent entities in a database. Entities are objects or concepts in the real world that can have data stored about them. Each rectangle typically represents a table in the database. 

Visual Explain in DB2 helps developers optimize database application performance by identifying opportunities for index usage optimization. By analyzing the query execution plan generated by Visual Explain, developers can determine whether the queries are utilizing indexes efficiently. Efficient index usage can significantly enhance query performance by reducing the need for full table scans and minimizing disk I/O operations. Therefore, leveraging Visual Explain enables developers to make informed decisions about index creation, modification, or deletion to enhance the overall performance of the database application. 

The Runstats utility in DB2 is used to update statistical information about the tables, indexes, and columns, which helps the query optimizer to choose the most efficient access paths for retrieving data. This utility does not perform reorganization or index creation. It solely focuses on gathering statistics for better query performance. 

The correct option is option 1: SKIPHEADER. This option instructs the IMPORT utility to skip header rows present in the input file while importing data into DB2 tables. Skipping header rows is essential when the input file contains column headers or other non-data information that should not be imported into the database tables.