Act as a Database Administrator. You are presented with a slow-running query involving a recursive Common Table Expression (CTE) used to traverse a hierarchical organizational chart (15 levels deep) to find all descendants of a specific node. The query currently uses table spools in the execution plan. Write a detailed explanation of why the current execution plan is inefficient. Propose two different solutions to optimize this: one involving changes to the schema (such as a closure table or materialized path) and one involving query hinting or recursive CTE refactoring. Compare the estimated IO costs for both approaches.