Which architecture should the solutions architect implement?

Explanations:

AWS Shield provides protection against DDoS attacks but does not directly improve application resilience to request rate increases. It focuses on security rather than scaling or performance.

Adding an Aurora Replica improves read scalability and offloads read traffic from the primary database instance, helping to handle increased request rates more effectively.

AWS Direct Connect provides dedicated network connections but does not directly address resilience or scalability for application traffic handling in a web architecture.

AWS Global Accelerator improves performance and availability for global applications but does not specifically address resilience to request rate increases within a single region.

Adding an Amazon CloudFront distribution can cache content at the edge locations, reducing the load on the Application Load Balancer and backend instances, thus improving resilience during traffic spikes.