The correct answer is D, Global reach. When a company uses AWS Regions, it is able to deploy its application in multiple geographical locations around the world. This deployment strategy allows the company to provide a lower latency and a better user experience for its customers globally, which is a key aspect of global reach. The other options, such as pay-as-you-go pricing (A), capacity forecasting (B), and economies of scale (C), are indeed advantages of cloud computing, but they do not directly relate to the specific scenario of increasing application availability to users in different countries through the use of AWS Regions.