Q: In an SSO solution, what is an identity provider?  

Correct option:
A system or entity which can verify and prove identity to other systems/entities involved in the SSO mechanism. Typically, this is also the entity that generates and verifies the SSO token.

Explanation:
In an SSO (Single Sign-On) solution, the identity provider (IdP) is the entity responsible for authenticating the user and verifying their identity. It provides identity information to other systems (called service providers) by generating and verifying the SSO token or authentication assertion, which allows users to access multiple applications without needing to authenticate again.

The IdP does not necessarily encrypt or provide passwords directly to other systems; instead, it manages user credentials and authentication.