What is the major organizational structure used in a hierarchical database model?

The major organizational structure used in a hierarchical database model is trees. This model organizes data in a tree-like structure where each record has a single parent and potentially many child records, resembling a hierarchy. At the top of this structure is the root node, which serves as the starting point for the hierarchy, while subsequent levels represent related records in a parent-child relationship.

In this model, each node in the tree is a record, and the connections between nodes reflect the relationships between data elements. This structure allows for efficient access and retrieval of data, particularly for scenarios where relationships are defined in a clear hierarchical manner, such as organizational charts or file systems.

The other options do not accurately represent the structure of a hierarchical database model. Flat tables imply a simple, two-dimensional arrangement without relationships between records. Network connections involve a much more complex structure that allows for multiple parent-child relationships, which extends beyond the limitations of a purely hierarchical model. Linear lists detail sequential data organization, which is not conducive to representing the hierarchical relationships inherent in this model.