Which type of Parameter employs a method query or complex expressions for member retrieval?

The type of Parameter that employs a method query or complex expressions for member retrieval is the Bound List. This type of parameter allows for dynamic retrieval of members based on certain conditions or logic, typically defined through queries or complex expressions. This provides significant flexibility, as it can adapt to various scenarios and changes in data without requiring a manual update.

Using a Bound List is particularly advantageous in situations where the data set is large or frequently changing, as it can automatically reflect the most current and relevant members based on the criteria established within the method query or expression. This capability enhances the interactive nature of reports and dashboards by ensuring the information presented is always aligned with the current state of the data.

For instance, a Bound List parameter could be used to filter a set of products based on their sales performance, dynamically including only those that meet specific sales thresholds defined in the query. This is a powerful feature when implementing OneStream solutions, as it enables users to craft more accurate and relevant analyses.

The other options are limited in that they either require static definitions (like the Static List), provide flat structures without complex retrieval methods (like the Flat List), or may simply list predefined members (like the Member List), hindering their flexibility compared to the Bound List.