Which type of network allows controlled and secure access to internal resources for external users?

The correct choice is extranet, as it refers specifically to a controlled network that enables external users to gain secure access to certain internal resources, such as documents, applications, or databases. An extranet extends the functionality of an intranet by allowing outside parties, such as suppliers, partners, or customers, to connect and interact with the organization's internal network while maintaining security protocols.

In contrast, a local area network (LAN) is confined to a specific geographic area, such as a single building or campus, and is primarily designed for internal use without facilitating external access. An intranet is a private network accessible only to an organization's staff, intended for internal communication and information sharing, but it does not extend to external users. A virtual private network (VPN) provides a secure connection over the internet, allowing remote users to access a private network, but does not inherently define the framework for granting access to external parties as the extranet does. Therefore, the extranet uniquely provides the controlled access required for external users to internal resources.