Load balancer and autoscaling are the solutions that should be implemented to address the requirements of optimizing system capacity and reducing cost for an e-commerce site in the cloud. A load balancer is a device or service that distributes incoming network traffic across multiple servers or instances based on various criteria, such as availability, performance, or location. A load balancer can improve system capacity by balancing the workload and preventing overloading or underutilization of resources. Autoscaling is a feature that allows cloud services to automatically adjust the number of servers or instances based on the demand or predefined rules. Autoscaling can reduce cost by scaling up or down the resources as needed, avoiding unnecessary expenses or wastage.