Final answer:
The question involves SQL operations such as UNION, INTERSECT, EXCEPT, and JOIN. The use of these operations depends on the desired result set. UNION is the most appropriate for combining unique result sets without duplicates.
Step-by-step explanation:
The question involves SQL database operations and is querying how to combine results from multiple SELECT statements. When you use the UNION operation, it combines the results of the two SELECT statements into a single result set, removing duplicate rows.
The INTERSECT operation would give you the common results between the multiple select statements, but since the select statements here are unique, INTERSECT would result in an empty set. The EXCEPT operation shows the difference between the first query and the subsequent queries, but again, as the select statements are unique, EXCEPT would merely show the first select. Lastly, the JOIN operation is not applicable here as it is used to combine rows from two or more tables based on a related column between them, and we do not have multiple tables or related columns specified here.
In terms of the correctness, none of the options provided are inherently more 'correct' than the others; it entirely depends on the result you wish to achieve with your query. Grouping the data differently, such as using ORDER BY to sort the UNION results, can be advantageous if you need to analyze the data in a specific order, but this isn’t part of the original question’s options.