Which cost-saving recommendation can AWS Cost Explorer provide?

AWS Cost Explorer provides cost-saving recommendations primarily focused on identifying underutilized or idle resources. Terminating an idle instance directly reduces ongoing compute costs, making it a common and impactful recommendation from Cost Explorer. The other options are generally outside the scope of Cost Explorer's direct recommendations. While changing a database engine or programming language could lead to cost savings, Cost Explorer doesn't analyze application-level architecture or code. Similarly, deploying a specific operating system isn't a direct cost-saving recommendation from Cost Explorer, which focuses on resource utilization rather than OS choice.