Answer: Set up additional service instances in other zones and load balance the traffic between all instances

The issue is that the API service is timing out due to high request volume and insufficient memory on a single Compute Engine instance, leading to SLI falling below SLO. Option A only adjusts the SLO to match current performance but does not address the root cause or improve availability. Option B increases memory on a single instance but retains a single point of failure and doesn't scale horizontally. Option D adds failover instances in other zones but keeps the primary instance handling all traffic, so it still risks memory exhaustion during peak loads. Option C is the best solution: deploying multiple instances across zones with load balancing distributes traffic, reduces per-instance load (preventing memory exhaustion), and enhances fault tolerance. This directly improves availability by handling high traffic and mitigating zonal failures.

Author: LeetQuiz Editorial Team