Which of the following services can be used as a web application firewall in AWS?

Answer options:

A.AWS EC2
B.AWS WAF
C.AWS Firewall
D.AWS Protection

Answer - B
The AWS Documentation mentions the following:
AWS WAF is a web application firewall that lets you monitor the HTTP and HTTPS requests that are forwarded to Amazon CloudFront or an Application Load Balancer. AWS WAF also lets you control access to your content.
For more information on AWS WAF, please refer to the below URL:
https://docs.aws.amazon.com/waf/latest/developerguide/waf-chapter.html