A service endpoint
Step-by-step explanation:
A service endpoint is a way to secure access to specific Azure resources by allowing only traffic from specific subnets or virtual networks to reach those resources. To ensure that VM1 can access storage1 over the Microsoft backbone, you should configure a service endpoint on the storage1 storage account, and then associate it with the virtual network or subnet that contains VM1. This will allow only traffic from that virtual network or subnet to reach storage1, and will ensure that VM1 can access storage1 securely and directly over the Microsoft backbone.
It is worth noting that, a VPN gateway is a way to connect an on-premises network to an Azure virtual network. The Azure Front Door service is a global, scalable, and highly available service that can be used to optimize the performance and security of your web applications. And a point to site (P2S) connection is a VPN connection that allows an individual client to connect to an Azure virtual network over the internet. In this case, none of these are the correct answer.