Methods for Accessing Resources between Company A and Company B

B.

The correct answer is B. Federation.

Federation is a method of allowing two different organizations to access each other's resources without having to merge their infrastructures. In this case, Company A and Company B can establish a trust relationship between their respective identity providers (IdPs), which allows users from one organization to access resources in the other organization using their own credentials.

Attestation is the process of verifying the identity and configuration of a device, such as a computer or mobile device, before allowing it to access resources on a network.

Single sign-on (SSO) is a method of authentication that allows users to access multiple applications or services with a single set of credentials. This is typically achieved using a central authentication service, such as Microsoft Active Directory, which handles authentication requests from multiple applications and services.

Kerberos is a network authentication protocol that is used to provide secure authentication for client/server applications. It is typically used in Microsoft Windows environments to authenticate users and services.

In summary, while all of these methods are related to authentication and access control, only Federation would allow two separate companies to access each other's resources without having to merge their infrastructures.