Solution

The correct answer is A, B

Key Points

• Hierarchical databases and network databases both use the concept of a parent-child relationship.
• In a hierarchical database, data are organized into a tree-like structure with a single root, to which all other data are linked in a hierarchy of parent-child relationships.​

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• Network databases allow multiple parent-child relationships, as the items can be accessed in multiple ways - not just from root to leave.

Additional Information

• Relational databases, contrastingly, use a model where data are organized as a set of formally-described tables from which data can be accessed or reassembled in many different ways without having to reorganize the tables themselves. They don't use the concept of parent-child relationships explicitly, as the relationships are based on common attributes between tables and not on an individual level of records.