What are the three primary delivery models of Cloud computing?

What are the three primary delivery models of Cloud computing?

A.
Infrastructure as a Service

B.
Application as a Service

C.
Software as a Service

D.
Platform as a Service

Explanation:
Regarding the Cloud Provider Perspective.Many resources can be offered as
services but the ORA conceptual model defines three broad categories of services listed below.
* Infrastructure as a Service (IaaS)
* Software as a Service (SaaS)
* Platform as a Service (PaaS)
Reference: Oracle Reference Architecture, Cloud Infrastructure, Release 3.0