Rapid Elasticity is a key characteristic of cloud computing, allowing resources to be quickly scaled up or down to accommodate the changing needs of an application or workload. This ability ensures that the company only uses and pays for the resources required at any given time, providing both flexibility and cost-efficiency. High Availability ensures uptime and reliability, but doesn't directly address scalability. Metered Utilization provides billing based on use, not the dynamic scaling of resources. File Synchronization is important for maintaining current data across multiple devices and is not concerned with infrastructure scalability.