The correct answer is AWS Trusted Advisor (C). AWS Trusted Advisor provides recommendations that help you follow AWS best practices, including monitoring service quotas. It evaluates your account by using checks, which include service limits (quotas), security, performance, and cost optimization. Trusted Advisor can notify you when you are approaching a service quota, allowing you to plan for requesting a quota increase before you exceed it. While Amazon CloudWatch (D) can be used to monitor various metrics and set alarms, it does not proactively monitor and plan for service quotas like Trusted Advisor does.