Why is it more efficient to handle 'IP Whitelisting' at the API Gateway rather than within each individual microservice?

1. A It prevents unauthorized traffic from ever entering your internal network, saving bandwidth and processing power for all backend services.
2. B It allows the Gateway to bypass the need for any internal firewalls completely.
3. C It ensures that the IP addresses of your users are deleted after every request to save disk space.
4. D It is the only way to allow microservices to communicate with the public internet.