A company will run critical production EC2 instances for at least three years and wants the lowest-cost pricing option. Which EC2 pricing model should they choose?

Reserved Instances (RIs) are ideal for applications with steady-state usage over a defined period, offering significant discounts (up to 75%) compared to On-Demand pricing. Since the company plans to run critical production instances for at least three years, a 3-year RI provides the lowest cost. On-Demand Instances are more expensive as they charge by the hour or second without long-term commitment discounts. Spot Instances are the cheapest but are unsuitable for critical production workloads because they can be interrupted with a two-minute warning. The AWS Free Tier is for new accounts to explore services and is not designed for sustained production workloads.