Final answer:
A new container instance named container1 can be connected to Subnet1, Subnet2, and Subnet3, assuming that no network security rules or service policies prevent the connection and that the subnets are appropriately configured.
Step-by-step explanation:
When deploying a container instance in Azure, you can typically connect it to any subnet within a virtual network as long as the networking rules and configurations allow it. However, Azure Container Instances (ACI) have some limitations and specific requirements around networking. Given that Subnet3 already has a connected container instance, it's clear that container instances can be deployed in that subnet. There's no information in the question that would prevent the container1 from being deployed to Subnet1 or Subnet2, assuming that networking and service policies allow this.
So, the answer to the question 'To which subnets can you connect container1?' is Subnet1, Subnet2, and Subnet3, assuming that all subnets are configured to support container instances and there are no network security rules or service policies preventing the connection.