An organization wants to control what types of network traffic are allowed to enter and leave its network and access its applications. Which security measure should the organization use?

2-Step Verification is an authentication control that verifies user identity at login; it does not inspect or filter network traffic.

Privileged access is an authorization concept governing what actions authenticated users may perform, not a network traffic control mechanism.

Encryption keys protect data confidentiality in transit or at rest but do not determine whether network traffic is permitted to reach an application.

Firewall rules inspect network packets and allow or deny traffic based on criteria such as source/destination IP, port, and protocol. In Google Cloud, VPC firewall rules are applied at the network level to control ingress and egress traffic to and from VM instances and other resources. This is the specific mechanism designed for traffic filtering and access control at the network boundary.