The correct answer is Document databases because they are well-suited for handling hierarchical data structures due to their document-oriented nature, where each document can contain nested information that represents such one-to-many relationships. They also offer schema flexibility, allowing for easy adjustments and evolution of the data structure as requirements change. Graph databases are excellent for relationships but do not inherently offer the same hierarchical structure and schema flexibility for document storage. Wide-column stores can handle large amounts of data with some flexibility, but are not optimized for complex hierarchical data as in the case of document databases. Key/value stores are highly performant for simple data models but lack the necessary features to efficiently manage complex hierarchical data structures with flexible schema changes.