A growing food delivery start-up intends to implement DDoS protection for its applications on AWS. Which fully managed service offering from AWS ensures customers protection from DDoS attack?

Answer options:

A.AWS Shield
B.AWS WAF - Web Application Firewall
C.AWS Firewall Manager
D.Amazon GuardDuty

Answer: A
Option A is CORRECT. AWS Shield is a fully managed service from AWS that ensures protection from DDoS attacks.
Option B is INCORRECT. AWS WAF helps us protect web applications and APIs against attacks by configuring various rules and conditions (like allow, block etc., based on defined conditions).
Option C is INCORRECT. AWS Firewall Manager enables management and configuration of firewall across AWS accounts and applications centrally.
Option D is INCORRECT. Amazon GuardDuty performs continuous monitoring to protect AWS account, S3 data and workloads from any malicious, unauthorized activities.
Reference: 
https://aws.amazon.com/shield/
https://aws.amazon.com/waf/
https://aws.amazon.com/firewall-manager/
https://aws.amazon.com/guardduty/