Which type of database management system is characterized by the flexibility to manage unstructured or semi-structured data?

The correct choice is NoSQL Databases because they are specifically designed to handle unstructured or semi-structured data, which traditional relational databases struggle with. NoSQL databases offer a variety of data models, such as document, key-value, column-family, and graph, allowing them to store and manage data in formats that do not require a fixed schema or relational structure. This versatility makes NoSQL databases particularly suitable for use cases involving large volumes of varied data, such as social media data, sensor data, and content management systems.

In contrast, relational databases rely on structured data with a predefined schema, making them less adaptable to changes in data formats. Data warehouses collect and manage structured data predominantly for analysis and reporting purposes, which does not lend itself to the flexibility required for unstructured data. Object-oriented databases aim to integrate object-oriented programming principles into database management, but they are not specifically designed for handling the diversity of unstructured data found in NoSQL systems. Thus, the strengths of NoSQL databases in managing varied data types make them the clear choice for this question.