What action should be taken to ensure that a new service deployed across multiple regions in a Managed Instance Group can automatically scale?

To ensure that a new service deployed across multiple regions in a Managed Instance Group (MIG) can automatically scale, it is essential to validate that resource requirements are within the available quota limits of each region. Quotas are limits set by Google Cloud on the usage of certain resources. If the necessary resources, such as CPUs or memory, exceed the regional quota, the MIG will not be able to scale up effectively, as instances cannot be created beyond the allowed limits.

This validation is critical for the automatic scaling functionality to work seamlessly across all regions. If a region has insufficient resources due to quota limitations, it may hinder the overall performance and responsiveness of the service, leading to potential downtimes or delays under increased load.

The other options do not address the core requirements for automatic scaling in the context of resource allocation and quota management. Selecting a specific machine type, monitoring performance results, or deploying the service in a single region with a global load balancer may not ensure that adequate resources are available in every region, which is essential for proper scaling of the service across the Managed Instance Group.