Which of the following is crucial prior to scaling a new production service across regions?

Ensuring resource availability in each region is critical before scaling a new production service across regions because it directly affects the application's ability to function correctly and efficiently. When a service is scaled, the resources needed to support the additional traffic and workload must be accessible in all targeted regions. This includes computing resources such as virtual machines, storage, and network capabilities. If there is insufficient resource availability, it can lead to service degradation, increased latency, or even outages, ultimately impacting user experience and service reliability.

The other options, while important for the operation and effectiveness of the service, do not address the immediate need for resource availability. Standard instance types can help optimize performance, but they do not substitute for having adequate resources ready to deploy. Monitoring tools like Cloud Trace are essential for tracking performance, but they come into play after the service is already functioning. Configuring Cloud Load Balancing is crucial for managing traffic across instances, yet it assumes that those instances are already available in the respective regions. Thus, ensuring that resources are in place is the fundamental first step in successfully scaling a service.