Explanation

The correct answer is C because deploying an application in multiple Availability Zones (AZs) directly supports the "design for failure and nothing will fail" principle.

Key Points:

• Availability Zones (AZs) are physically separate data centers within an AWS Region
• Each AZ has independent power, cooling, and networking
• By deploying across multiple AZs, your application becomes fault-tolerant
• If one AZ experiences an outage, your application continues running in other AZs

Why Other Options Don't Apply:

• A: A single EC2 instance with a load balancer still represents a single point of failure - if the instance fails, the application goes down
• B: Cost-effectiveness doesn't inherently address fault tolerance or failure design
• D: Monitoring helps detect failures but doesn't prevent them or provide redundancy

AWS Best Practice:

AWS recommends distributing resources across multiple AZs to achieve high availability and fault tolerance. This approach ensures that your application remains available even if an entire data center (AZ) becomes unavailable.

For more information, refer to AWS documentation on Regions and Availability Zones.