For short-duration workloads that can be interrupted and where cost savings are a priority, which Amazon EC2 instance purchasing option should be used?

Spot Instances are the correct choice because they allow you to bid on unused EC2 capacity, offering significant cost savings (up to 90% compared to On-Demand prices). They are ideal for fault-tolerant, flexible applications that can handle interruptions, such as batch processing, data analysis, or stateless web servers. On-Demand Instances are charged by the second or hour with no long-term commitment, suitable for unpredictable workloads that cannot be interrupted, but they are more expensive. Reserved Instances offer a significant discount for committing to a 1- or 3-year term, best for steady-state, predictable workloads. Dedicated Instances run on single-tenant hardware, providing isolation but at a higher cost, typically for strict compliance requirements.