Explanation

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

• Usage Pattern: The application runs only once per week and once at month-end, which means the instances are used infrequently and irregularly
• Flexibility: On-Demand Instances allow you to start and stop instances as needed without long-term commitments
• Cost Efficiency:
  • Reserved Instances (Standard or Convertible) require 1-3 year commitments and are cost-effective only for steady-state, predictable workloads
  • On-Demand Capacity Reservations reserve capacity but still charge for the entire reservation period, making them expensive for intermittent use
  • On-Demand Instances charge only for actual compute time used, which aligns perfectly with this intermittent usage pattern

Key Points:

• When instances can be stopped when not in use, On-Demand pricing provides the best value for irregular workloads
• Reserved Instances are designed for consistent, predictable usage over long periods
• The ability to stop instances eliminates the need for capacity reservations or long-term commitments

This approach minimizes costs while maintaining the required flexibility for the reporting schedule.