A startup expects unpredictable traffic spikes for their web application. Which EC2 pricing model is MOST cost-effective for the baseline capacity?

Correct answer: Reserved Instances (1-year)

Option B is correct because Reserved Instances with a one-year commitment provide a significant discount (up to 72%) over On-Demand pricing and are ideal for predictable baseline capacity, giving the startup cost predictability for the steady-state load while they handle spikes through other means. Option A is wrong because Spot Instances can be interrupted by AWS with two minutes notice when capacity is reclaimed, making them unsuitable for baseline web application capacity that must remain available. Option C is wrong because On-Demand Instances carry the highest per-hour cost with no commitment discount, which is less cost-effective than Reserved Instances for sustained baseline workloads. Option D is wrong because Dedicated Hosts provide an entire physical server for compliance or licensing needs and are the most expensive option, far exceeding what a startup needs for a standard web application baseline.