The correct answer is C because a managed instance group allows for autoscaling based on demand, which can then be efficiently managed behind a load balancer as a backend service. This approach leverages GCP's capabilities for load balancing and autoscaling, ensuring your application can handle varying traffic loads dynamically.

• Option A is incorrect because it only exposes a static image, not the application.
• Option B is incorrect because unmanaged instance groups do not support autoscaling with instance templates.
• Option D is incorrect because unmanaged instance groups lack autoscaling features, making them unsuitable for dynamic traffic handling.