Service insertion policies is correct because it is the feature that explicitly steers network flows through designated security appliances or service chains before the traffic reaches its final destination.

Service insertion policies work by matching traffic and then redirecting or chaining that traffic to inline services such as firewalls, intrusion detection systems, or other security appliances so that inspection or processing occurs along a defined path.

VPC firewall rules are incorrect because they are used to filter or allow traffic at the virtual network level and they do not by themselves steer flows through external security appliances.

Endpoint groups are incorrect because they are used to group workloads for policy application and segmentation and they do not implement service chaining to route traffic through appliances.

Access control lists are incorrect because they provide packet level filtering based on addresses and ports and they do not ensure that traffic is routed through designated security appliances for inspection.

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