AWS Certified Cloud Practitioner

Explanation

On-Demand Instances are the most cost-effective choice for this scenario because:

• Short-term workloads: On-Demand Instances are billed by the second with no long-term commitments, making them ideal for unpredictable, short-duration workloads
• Irregular patterns: When usage patterns are inconsistent and cannot be predicted, On-Demand pricing avoids the waste of paying for reserved capacity that goes unused
• Cannot be interrupted: Unlike Spot Instances (which are not listed here), On-Demand Instances provide guaranteed availability and cannot be interrupted by AWS
• No upfront costs: There are no upfront payments or long-term contracts required

Why other options are less suitable:

• Reserved Instances: Require 1-3 year commitments and are cost-effective only for predictable, steady-state workloads
• Savings Plans: Also require 1-3 year commitments for consistent usage patterns
• Dedicated Instances: Provide physical isolation but are more expensive and don't address the irregular workload pattern

For workloads that are short-term, irregular, and cannot tolerate interruption, On-Demand Instances provide the optimal balance of flexibility and cost-effectiveness.