Which factor most constrains the global scalability of large-scale hydroelectric power compared to solar or wind energy?

💡 Explanation:

Global scalability of large-scale hydropower is fundamentally limited by the finite number of suitable river sites that offer the necessary elevation drop and valley structure (topography) for dam construction, and the vast land area required for reservoirs. Solar and wind energy, while having their own challenges, are not constrained by such specific, non-replicable geographical features, allowing for much broader global deployment potential, making B the primary constraint on scalability.