AWS Certified Cloud Practitioner

Explanation

Scalability is the correct answer because:

• Scalability refers to the ability of a system to handle increased workload by adding resources (scale out) or increasing the capacity of existing resources (scale up)
• In this scenario, the EC2 instances need to "accommodate unpredictable increases in traffic" - this is exactly what scalability provides
• AWS Auto Scaling can automatically add or remove EC2 instances based on traffic demands
• Elastic Load Balancing distributes traffic evenly across the fleet

Why not the other options:

• Resilience: Focuses on fault tolerance and recovery from failures, not handling traffic increases
• Security: Concerns protection of data and resources, not capacity management
• Agility: Refers to speed of deployment and innovation, not specifically handling traffic fluctuations

Scalability allows the company to automatically adjust computing capacity to maintain performance during traffic spikes while keeping costs optimized during low-traffic periods.