Amazon EC2 security groups is the correct option because they provide a stateful instance level virtual firewall that you can attach to multiple instances so the same inbound and outbound rules apply across them.

Security groups are stateful so return traffic is automatically allowed when outgoing traffic is permitted and they operate at the instance level so you can reuse the same group for many instances to ensure consistent enforcement.

Network Access Control Lists (ACL) are subnet scoped and stateless and they are not attached to individual instances so they do not meet the instance scoped requirement.

Virtual private gateways (VPG) are used for VPN connectivity into a VPC and they do not act as firewalls for EC2 instances.

Route table controls traffic routing inside the VPC and it does not provide packet filtering or firewall capabilities.

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