Answer: Achieving economies of scale

The correct answer is D, Economies of scale. AWS, as a cloud service provider, benefits from economies of scale by aggregating usage from a vast number of customers. This aggregation allows AWS to negotiate better pricing with hardware and software vendors, optimize resource utilization, and spread infrastructure costs across a large customer base. The cost savings achieved through these economies of scale are then passed on to customers in the form of lower variable costs. While the pay-as-you-go pricing model (A) is a feature of AWS services, it is an outcome of the economies of scale that enable such pricing. High availability (B) and global reach (C) are also benefits of cloud computing, but they do not directly relate to the ability to offer lower variable costs due to high purchase volumes.

Author: LeetQuiz Editorial Team