The correct answer is A, Standard Reserved Instances. This option is the most cost-effective for long-term, steady-state workloads like the one described in the question. By committing to a 1-year term, the company can benefit from significant savings of up to 75% off On-Demand pricing. This commitment provides cost predictability and is ideal for a workload that is expected to run continuously for the entire year without changes in instance specifications. While On-Demand Instances (B) offer flexibility, they are more expensive in the long run. Spot Instances (C) can be cost-effective but are not suitable for production databases as they can be interrupted. Convertible Reserved Instances (D) offer flexibility but at a lower discount rate than Standard Reserved Instances.