What type of server is designed specifically to store, organize, and retrieve data efficiently?

A database server is specifically designed to store, organize, and retrieve data efficiently. This type of server utilizes database management systems (DBMS) to handle structured data, which allows for complex queries, data manipulation, and efficient data retrieval processes. Database servers can manage large volumes of data and provide secure access for multiple users and applications concurrently.

In contrast, a file server is primarily focused on storing files and providing access over a network. While it allows users to share documents and other types of files, it does not offer the same level of data querying and organization capabilities as a database server.

A web server's primary function is to host websites and serve web pages to users. It processes web requests and serves content over the internet, rather than managing and retrieving structured data in an organized manner.

A mail server is dedicated to managing email communications, routing messages between users, storing mailboxes, and ensuring secure transmission of email. While it deals with data, its focus is on email rather than the efficient storage and retrieval of diverse data sets.

Thus, the role of a database server is distinct in focusing on managing relational or structured data efficiently, making it the correct choice.