The core requirement here is handling fluctuating traffic (spikes up to 4x capacity) in a cost-effective way.

Horizontal Autoscaling: Vertex AI endpoints support autoscaling by setting a min-replica-count and a max-replica-count. By increasing the maximum replicas to 6 (Option B), the service can scale out horizontally to meet the 4x traffic demand and, more importantly, scale back down when traffic subsides. This prevents paying for idle resources.

Why other options are incorrect:

Option A: TPUs are designed for training large neural networks (TensorFlow/JAX/PyTorch). They are not supported for standard scikit-learn deployments and would be extremely over-provisioned/expensive for this use case.

Option C: Switching to a massive 32-vCPU machine (Vertical Scaling) is expensive because you pay for that high capacity 24/7, even when traffic is low. It lacks the elasticity needed for fluctuating loads.

Option D: Manual intervention based on alerts is slow and prone to downtime during traffic spikes. Vertex AI ' s native autoscaling is the managed, automated way to handle this.