You need to add VM1 and VM2 to the backend pool of LB1. What should you do first?

VM1 is already in VNET1/Subnet1.
VM2 is on VNET1/Subnet2, and must be moved to VNET1/Subnet1.
Note:
Create an internal Basic Azure Load Balancer named LB1 and connect the load balancer to VNET1/Subnet1

Reference:
https://docs.microsoft.com/en-us/azure/load-balancer/quickstart-load-balancer-standard-internal-portal