Answer: An Internet-routable IP address (static) of the customer gateway's external interface for the on-premises network
Step-by-step explanation:
Based on the information given, an Internet-routable IP address (static) of the customer gateway's external interface for the on-premises network need to be configured outside of the VPC for them to have a successful site-to-site VPN connection.
The Internet-routable IP address will be used in the identificatiob of each computer through the use of the Internet Protocol for the communication over a network.