The correct answer is B because this command sets the default region for future gcloud commands, ensuring that the specified region is used unless overridden by a command parameter.

• Option A is incorrect because Cloud Shell does not default to the location from which it's launched.
• Option C is incorrect because this command is intended for setting a zone, not a region.
• Option D is incorrect because establishing a VPN to a specific subnet does not influence the gcloud command's default region.