Explanation

AWS Shield Advanced is the correct answer because it provides comprehensive DDoS protection with proactive mitigation assistance:

• DDoS Protection: AWS Shield Advanced offers enhanced DDoS protection for AWS resources including EC2, ELB, CloudFront, Route 53, and Global Accelerator
• Proactive Mitigation: It includes 24/7 access to the AWS DDoS Response Team (DRT) for proactive mitigation assistance during attacks
• Cost Protection: Provides financial protection against scaling costs resulting from DDoS attacks
• Advanced Threat Intelligence: Offers detailed attack diagnostics and visibility

Why other options are incorrect:

• Amazon GuardDuty: A threat detection service that monitors for malicious activity and unauthorized behavior, but not specifically designed for DDoS protection
• AWS Network Firewall: A managed network firewall service for network traffic filtering, but not specialized DDoS protection
• AWS WAF: A web application firewall that protects against common web exploits, but doesn't provide the comprehensive DDoS protection and proactive assistance of Shield Advanced

AWS Shield comes in two tiers: Standard (free, automatic protection) and Advanced (paid, with enhanced features including proactive mitigation assistance).