Measured service is the aspect of cloud computing that pertains to cloud services and resources being billed in a metered way, based only on the level of consumption and duration of the cloud customer. Although they sound similar to the correct answer, none of the other choices is the actual cloud terminology.

The CPU and memory resources of an environment together comprise its "computing" resources. Cloud environments, especially public clouds, are enormous pools of resources for computing and are typically divided among a large number of customers with constantly changing needs and demands. Although storage and networking are core components of a cloud environment, they do not comprise its computing core. Software, much like within a traditional data center, is highly subjective based on the application, system, service, or cloud computing model used; however, it is not one of the core cloud components.

The question-is describing the Platform as a Service (PaaS) cloud offering, and as such, structured and unstructured storage types will be available to the customer. Volume and object are storage types associated with IaaS, and although the other answers present similar-sounding storage types, they are a mix of real and fake names.

Firewalls work at the network level and control traffic based on the source, destination, protocol, and ports. Whether or not the traffic is encrypted is not a factor with firewalls and their decisions about routing traffic. Firewalls work primarily with IP addresses, ports, and protocols.

Within IaaS, where the cloud customer is responsible for everything beyond the physical network, the number of users on a system would not be a factor in billing or service charges. The core cloud services for IaaS are based on the memory, storage, and CPU requirements of the cloud customer. Because the cloud customer with IaaS is responsible for its own images and deployments, these components comprise the basis of its cloud provisioning and measured services billing.

An injection attack is where a malicious actor sends commands or other arbitrary data through input and data fields with the intent of having the application or system execute the code as part of its normal processing and queries. This can trick an application into exposing data that is not intended or authorized to be exposed, or it can potentially allow an attacker to gain insight into configurations or security controls. Missing function-level access control exists where an application only checks for authorization during the initial login process and does not further validate with each function call. Cross-site request forgery occurs when an attack forces an authenticated user to send forged requests to an application running under their own access and credentials. Cross-site scripting occurs when an attacker is able to send untrusted data to a user's browser without going through validation processes.

The goal with any cloud-hosting setup is for the cloud customer to be able to perform most or all its functions for service provisioning and configuration without any need for support from or interaction with the cloud provider beyond the automated tools provided. To fulfill the tenants of on-demand self-service, required interaction with the cloud provider--either half time, full time, or a commensurate amount of time based on the contract--would be in opposition to a cloud's intended use. As such, these answers are incorrect.

No matter what form they come in, "services" are obtained or purchased by a cloud customer from a cloud service provider. Services can come in many forms--virtual machines, network configurations, hosting setups, and software access, just to name a few. Hosting and servers--or, with a cloud, more appropriately virtual machines--are just two examples of "services" that a customer would purchase from a cloud provider. "Customers" would never be a service that's purchased.

The store phase occurs immediately after the create phase, and as data is committed to storage structures, the first opportunity for security controls to be implemented is realized. During the create phase, the data is not yet part of a system where security controls can be applied, and although the use and share phases also entail the application of security controls, they are not the first phase where the process occurs.