A retail startup wants to avoid buying costly servers but needs capacity that grows during seasonal spikes. Which cloud benefit applies?

Elasticity is the correct answer because it describes the ability of a cloud system to automatically and dynamically adjust its resources (like compute power or storage) to meet fluctuating demand. This perfectly addresses the startup's need for capacity that grows during seasonal spikes and shrinks when demand is low, without manual intervention. Scalability (A) is the ability to increase or decrease resources, but it often implies manual intervention or pre-planned adjustments, not the automatic, dynamic response of elasticity. While related, elasticity is a more precise fit for automatic scaling. Economies of scale (B) refers to the cost advantages that enterprises obtain due to their size, allowing cloud providers to offer services at lower prices, but it doesn't directly describe the dynamic resource adjustment. Capital expenditure (C) refers to the upfront cost of purchasing physical assets like servers, which the startup wants to avoid, but it's a financial term, not a cloud benefit describing resource adjustment.