Answer:
b) Use a third-party product as the Identity Provider for both Salesforce and Google Apps and manage the provisioning from there.
d) Use Salesforce as the Identity Provider and Google Apps as a Service Provider and configure User Provisioning for Connected Apps.
Explanation:
When using a third party as identity provider (for creating and managing prinipal identity information and providing authentication service to both Salesforce and Google Apps).
You can also use Salesforce as the identity provider for all users in Universal Containers, while Google Apps will function as a service provider.