Which AWS service or feature offers security for a VPC by acting as a firewall...

A network access control list (network ACL) is a feature that acts as a firewall for controlling traffic in and out of one or more subnets in a virtual private cloud (VPC). Network ACLs can be configured with rules that allow or deny traffic based on the source and destination IP addresses, ports, and protocols1. AWS Security Hub is a service that provides a comprehensive view of the security posture of AWS accounts and resources2. Security groups are features that act as firewalls for controlling traffic at the instance level3. AWS WAF is a web application firewall that helps protect web applications from common web exploits4.