Explanation

AWS Trusted Advisor is the correct answer because:

• Cost Explorer is primarily for visualizing and analyzing AWS costs and usage over time
• AWS Trusted Advisor provides real-time guidance to help provision resources following AWS best practices, including cost optimization, performance, security, and fault tolerance recommendations
• Amazon Inspector is a security vulnerability assessment service that helps improve security and compliance
• AWS Budgets is used to set custom budgets that alert when costs or usage exceed budgeted amounts

AWS Trusted Advisor inspects AWS environments across multiple categories:

• Cost Optimization: Identifies unused resources and opportunities to reduce costs
• Performance: Recommends improvements for service limits, latency, and resource utilization
• Security: Checks for security gaps and vulnerabilities
• Fault Tolerance: Ensures high availability and backup configurations
• Service Limits: Monitors service usage against limits

This makes AWS Trusted Advisor the comprehensive tool that provides both cost savings and system performance improvement recommendations.