What is the best option to store the session state?

Explanations:

Amazon ElastiCache provides a fast in-memory caching solution, ideal for storing session states with low latency and high availability, making it suitable for scalable applications.

Amazon CloudFront is a content delivery network (CDN) that caches static content but is not designed for session state storage, as it focuses on distributing content rather than managing dynamic user session data.

Amazon S3 is an object storage service that is not optimized for high-speed session state retrieval or management, as it introduces higher latencies compared to in-memory solutions like ElastiCache.

Enabling session stickiness on elastic load balancers can help maintain user sessions with a specific instance, but it does not provide a fault-tolerant or scalable solution for session state management across multiple instances.