Cloud environments depend heavily on API calls for management and automation. Any vulnerability with the APIs can cause significant risk and exposure to all tenants of the cloud environment. Resource pooling and elasticity could both be impacted by insecure APIs, as both require automation and orchestration to operate properly, but automation is the better answer here. Redundancy would not be directly impacted by insecure APIs.

Explanation
Power distribution units are internal to a data center and supply power to internal components such as racks, appliances, and cooling systems. As such, they are considered an internal redundancy.

Explanation
A reservation guarantees to a cloud customer that they will have access to a minimal level of resources to run their systems, which will help mitigate against DoS attacks or systems that consume high levels of resources.
A limit refers to the enforcement of a maximum level of resources that can be consumed by or allocated to a cloud customer, service, or system. Both guarantee and assurance are terms that sound similar to reservation, but they are not correct choices.

Explanation
An injection attack is where a malicious actor will send 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 could 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.

Explanation/Reference:
Explanation:
The hypervisor level, as a backend cloud infrastructure component, is not a unit where limits may be applied to control resource utilization. Limits can be placed at the service, virtual machine, and cloud customer levels within a cloud environment.