Solution

The JOIN operation in SQL is used to combine rows from two or more tables based on a related column between them. This is essential in relational database management systems (RDBMS) when you need to combine data stored in separate tables based on a common field. There are various types of joins, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN, which allow you to control how the data from the related tables is combined. JOIN is fundamental in SQL queries to link data across tables and perform meaningful analysis. The other options are incorrect because: • Option 2 (UNION) combines the results of two SELECT queries, but it does not join tables based on a common column. It simply appends rows from the result sets. • Option 3 (INTERSECT) returns only the rows that are present in both SELECT query results, which is different from joining tables. • Option 4 (SELECT) is a basic SQL command used to retrieve data from a database but does not combine tables. • Option 5 (GROUP BY) is used to group rows based on a specified column, typically for aggregation, and does not combine tables.