Your Team Needs to Make Sure That Their Backend Database

Your team needs to make sure that their backend database can only be accessed by the frontend application and no other instances on the network. How should your team design this network?

A) Create an ingress firewall rule to allow access only from the application to the database using firewall tags.
B) Create a different subnet for the frontend application and database to ensure network isolation.
C) Create two VPC networks, and connect the two networks using Cloud VPN gateways to ensure network isolation.
D) Create two VPC networks, and connect the two networks using VPC peering to ensure network isolation.