The explain statement will return a row for each _________ used in a statement.

The explain statement is a powerful tool in Appian that helps users understand the execution plan of their queries. When used, it generates a row for each table that is accessed within the query. This functionality is essential for optimizing performance and debugging, as it provides insight into how tables are being utilized, joined, and transformed within the larger context of the statement.

Focusing on tables allows developers to see the relationships and operations that are happening at the database level. By understanding which tables are accessed and how they interact in a query, one can identify potential bottlenecks and make necessary adjustments to improve execution times and resource usage.

The other options, while relevant to understanding aspects of queries, do not accurately represent what the explain statement targets. Functions, queries, and columns may all be part of a query execution, but the explain statement specifically highlights the tables involved, making this understanding crucial for effective performance tuning and query optimization in Appian applications.