Elastic Load Balancing is the correct choice because it automatically routes inbound traffic across healthy EC2 instances in multiple Availability Zones and it increases application resilience without requiring any changes to the application code.

Elastic Load Balancing performs health checks and forwards traffic only to healthy targets and it spreads requests across instances in different AZs so the web tier remains available when individual instances fail. The load balancer sits in front of the instances and handles distribution and failover so application code does not need to be modified.

AWS Global Accelerator improves global availability and performance by using static anycast IPs and routing to regional endpoints and it is typically used in front of regional load balancers rather than directly balancing traffic across EC2 instances inside a VPC.

Amazon DynamoDB is a fully managed NoSQL database and it does not distribute inbound client requests to EC2 web servers or provide compute layer fault tolerance and therefore it does not meet the requirement to spread traffic across instances.

Amazon ElastiCache offers in-memory caching to improve performance and it does not act as a request load balancer so it will not distribute inbound client traffic across application servers or add the desired resilience to the compute layer.

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