The correct choice is Plan for failure because the deployment spreads the web tier across multiple Availability Zones and places it behind a load balancer so users can still reach the site when a single zone goes down.

Plan for failure is appropriate because the architecture assumes components may fail and builds redundancy and failover into the design. Distributing instances across AZs and using a load balancer increases fault tolerance and supports high availability by reducing single points of failure.

Support elasticity is incorrect because elasticity focuses on matching capacity to demand with mechanisms such as Auto Scaling rather than on cross zone resilience.

Automate operations is incorrect because placing resources in multiple Availability Zones and using a load balancer does not by itself automate deployment or operational tasks.

Prioritize agility is incorrect because agility refers to rapid development and iteration practices and not specifically to designing for availability and fault tolerance.

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