"question 3 : an organization is using a saas cloud-based service shared with another organization. what type of cloud-based deployment model does this describe? "

Community cloud deployment model

Explanation: Community cloud deployment model is the model helps in providing the cloud based service to more than one organizations. It works for the community to provide software as service(SaaS).

There are still certain limitation in the number of organizations in the community. The service is examined by any service provider acting as third party or the governing organization.The governing of security and management is done by them.