SaaS supports multiple users and provides a shared data model through . . . . . . . . model.

Multi-tenancy is a common architecture for SaaS applications, as it allows providers to offer a scalable and cost-effective service.

Single-tenancy is an architecture in which each customer has their own dedicated instance of an application. This architecture is more secure and reliable than multi-tenancy, but it is also more expensive.

Multiple-instance is an architecture in which multiple instances of an application are run on separate servers. This architecture is more scalable than single-tenancy, but it is also more complex to manage.

In conclusion, the correct answer is B. multi-tenancy.