Explanation
The infrastructure service capability gives the cloud customer substantial control in provisioning and configuring resources, including processing, storage, and network resources.

Integrity refers to the trustworthiness of data and whether its format and values are true and have not been corrupted or otherwise altered through unauthorized means. Confidentiality refers to keeping data from being access or viewed by unauthorized parties. Accessibility means that data is available and ready when needed by a user or service. Validity can mean a variety of things that are somewhat similar to integrity, but it's not the most appropriate answer in this case.

Explanation
Limits are put in place to enforce a maximum on the amount of memory or processing a cloud customer can use. This can be done either on a virtual machine or as a comprehensive whole for a customer, and is meant to ensure that enormous cloud resources cannot be allocated or consumed by a single host or customer to the detriment of other hosts and customers.

It is imperative that applications do checks when each function or portion of the application is accessed to ensure that the user is properly authorized. Without continual checks each time a function is accessed, an attacker could forge requests to access portions of the application where authorization has not been granted.
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. Cross-site scripting occurs when an attacker is able to send untrusted data to a user's browser without going through validation processes. 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.