Final answer:
The primary type of database used in applications today is the Relational database. It is widely adopted due to its ability to store and manipulate structured data effectively with tables and relations. Less common database types include hierarchical, network, and archival databases.
Step-by-step explanation:
The primary type of database used in applications today is B. Relational. Relational databases store data in tables, where each table represents a different type of entity. Data in one table can be related to data in another, using foreign keys, which makes this type of database particularly powerful for storing and manipulating structured data.
In contrast, hierarchical databases, which organize data in a tree-like structure, and network databases, which allow more complex relationships between data, are less commonly used today. Archival databases are specialized for storing historical records and are not typically used in most day-to-day applications. Relational databases are well-suited for a wide range of applications, from simple ones like a personal to-do list, to complex enterprise resource planning systems. Popular examples of relational database management systems include MySQL, PostgreSQL, and Oracle.