A. Set up a geolocation routing policy. Send the traffic that is near us-west-1 to the on-premises data center. Send the traffic that is near eu-central-1 to eu-central-1.
B. Set up a simple routing policy that routes all traffic that is near eu-central-1 to eu-central-1 and routes all traffic that is near the on-premises datacenter to the on-premises data center.
C. Set up a latency routing policy. Associate the policy with us-west-1.
D. Set up a weighted routing policy. Split the traffic evenly between eu-central-1 and the on-premises data center.