Correct Answer: A. Abstraction
Explanation of Concepts:
Abstraction
Thus, abstraction in cloud computing simplifies the complex details of infrastructure so that a user can access and control resources without having to understand the hardware and software that lie underneath. As a principle, this concept is simple because it enhances friendliness in use, simplifies resource management, and optimizes the cloud experience by hiding technical complexities.
Reliability
Reliability ensures cloud services are available, secure and reliable, and functioning at an optimal rate. Although reliability is needed for the maintenance of service quality and uptime, it extends to the abstraction layer and hence it comes after it and not vice versa.
Efficient
While in cloud computing, productivity is concerned about making the most of the available resources to meet business needs, productivity is rather the consequence of the proper implementation of cloud systems and abstraction rather than a base concept in cloud computing.
Conclusion
All three concepts-Abstraction, Reliability, and Productivity-are part of the cloud. Abstraction is the most basic one of these. It forms the basis of how users interact with cloud services so that they can harness the power of the cloud without necessarily understanding how it works inside.