The requirements for a web application state that it must be architected for high availability. The web application consists of front-end web server and back-end database server components…

Having only one front-end web server creates a single point of failure for the web application, failing to meet the high availability requirement for the entire application.

While having two of each server type provides some redundancy, it doesn't explicitly mention load balancing for web servers or clustering for database servers, which are key mechanisms for achieving active-active high availability and automatic failover, potentially leading to less efficient use or slower recovery compared to D.

Having only one back-end database server creates a single point of failure for the database, making the application vulnerable to database outages and failing to meet the high availability requirement.

This solution provides high availability for both the front-end and back-end components. Two load-balanced front-end web servers distribute traffic and ensure continuous service even if one web server fails. Two clustered back-end database servers provide redundancy and failover capabilities for the database, preventing a single point of failure and ensuring data availability, which is crucial for overall application uptime.