What SAML SSO flow should an Architect recommend for UC?

Universal Containers (UC) wants its users to access Salesforce and other SSO-enabled applications from a custom web page that UC magnets. UC wants its users to use the same set of credentials to access each of the applications.

What SAML SSO flow should an Architect recommend for UC?
A . SP-Initiated with Deep Linking
B. SP-Initiated
C. IdP-Initiated
D. User-Agent

Answer: C