A company's website is used to sell products to the public.

AWS WAF is a web application firewall that helps protect web applications from common web exploits that could affect application availability, compromise security, or consume excessive resources. AWS WAF allows users to create rules that block, allow, or count web requests based on customizable web security rules. One of the types of rules that can be created is an IP match rule, which allows users to specify a list of IP addresses or IP address ranges that they want to allow or block. By modifying the configuration of AWS WAF to add an IP match condition to block the malicious IP address, the solution architect can prevent the attacker from accessing the website through the CloudFront distribution and the ALB.

The other options are not correct because they do not effectively block the malicious IP address from accessing the website. Modifying the network ACL on the CloudFront distribution or the EC2 instances in the target groups behind the ALB will not work because network ACLs are stateless and do not evaluate traffic at the application layer. Modifying the security groups for the EC2 instances in the target groups behind the ALB will not work because security groups are stateful and only evaluate traffic at the instance level, not at the load balancer level.