Which method allows the application to handle scaling automatically under varying loads?

Implementing autoscaling mechanisms in Cloud Run is the correct choice because it allows applications to dynamically adjust the number of active instances based on the current load. Cloud Run is designed to automatically manage the scaling of containerized applications. It evaluates incoming traffic and scales the number of container instances up or down in response to the demand. This capability means the application can efficiently handle variable workloads without manual intervention, leading to optimal resource utilization and cost-effectiveness.

The other options would not provide the same dynamic scaling benefits. A static server architecture, for example, lacks the flexibility to adapt to fluctuating demand, which can lead to either resource waste during low load or insufficient capacity during peak times. Utilizing fixed resource allocations limits the ability to respond to changes in load, as it requires pre-defined settings that do not adjust automatically. Enhancing traditional load balancing methods may improve performance but does not inherently provide the scalability needed to automatically manage varying loads as Cloud Run does.