What should a solutions architect do to mitigate the slow response times and timeout errors while minimizing operational overhead?

Explanations:

Increasing the instance size of the web server may provide temporary relief, but it does not address the underlying issue of scalability during high traffic periods. This option does not improve fault tolerance or handle the 400% traffic increase effectively.

Adding an Application Load Balancer and an additional web server helps distribute traffic but does not dynamically scale the web servers based on demand. It may improve performance, but without Auto Scaling, it could lead to inefficiencies and higher costs during non-peak periods.

Implementing Amazon EC2 Auto Scaling along with an Application Load Balancer allows for dynamic scaling of web servers based on traffic demand. This ensures that during high traffic periods, additional instances are launched automatically, thus reducing response times and preventing timeout errors. It also minimizes operational overhead by automating scaling activities.

Deploying an Amazon ElastiCache cluster can improve performance by caching frequently accessed data, but it does not address the scaling of the web server resources. While it may help reduce load on the database, it does not solve the core issue of handling increased traffic efficiently.