The correct answer is: A. network database model
A network database model is a database model in which data is organized into records and sets. Records are similar to rows in a relational database, and sets are similar to columns. Records are linked to each other through sets.
A relational database model is a database model in which data is organized into tables. Tables are made up of rows and columns. Each row represents a single entity, such as a customer or product. Each column represents an attribute of that entity, such as the customer’s name or the product’s price.
An object-oriented database model is a database model in which data is organized into objects. Objects are similar to records in a relational database, but they also have properties and methods. Properties are similar to attributes, and methods are similar to functions.
The network database model is not a database model because it is not a widely used or well-known database model. It is not as popular as the relational database model or the object-oriented database model.