Final answer:
The cloud computing model where consumers install applications and the OS, but the service provider controls the infrastructure, is known as Infrastructure as a Service (IaaS).
Step-by-step explanation:
The scenario described in the question pertains to a model of cloud computing where consumers can install applications, including the operating system (OS) and custom applications, but do not control the underlying cloud infrastructure. This model is known as Infrastructure as a Service (IaaS). In IaaS, the service provider manages the physical servers, network, and storage, while the consumer manages the virtual machines, including OS, middleware, and applications.
The correct answer to the question is (c) IaaS. Other models like Software as a Service (SaaS) and Platform as a Service (PaaS) offer different levels of control. In SaaS, the provider controls both the infrastructure and the applications, while in PaaS, the provider controls the infrastructure and the consumer manages applications to a greater extent than in IaaS but does not have control over the operating system.