What approach should an Architect recommend to UC?

Universal Containers (UC) has five Salesforce orgs (UC1, UC2, UC3, UC4, UC5). of Every user that is in UC2, UC3, UC4, and UC5 is also in UC1, however not all users 65* have access to everyorg. Universal Containers would like to simplify the authentication process such that all Salesforce users need to remember one set of credentials. UC would like to achieve this with the least impact to cost and maintenance .

What approach should an Architect recommend to UC?
A . Purchase a third-party Identity Provider for all five Salesforce orgs to use and set up JIT user provisioning on all other orgs.
B. Purchase a third-party Identity Provider for all five Salesforce orgs to use, but don’t set up JIT user provisioning for other orgs.
C. Configure UC1 as the Identity Provider to the other four Salesforce orgs and set up JIT user provisioning on all other orgs.
D. Configure UC1 as the Identity Provider to the other four Salesforce orgs, but don’t set up JIT user provisioning for other orgs.

Answer: B