Why Correct: Kolkata Metropolitan Area (KMA) is a formally defined administrative region established by the Kolkata Metropolitan Development Authority, with legally specified boundaries covering Kolkata and surrounding urban areas for planning purposes.
Distractor Analysis: Homogeneous regions share uniform characteristics like climate or culture, which doesn't apply to KMA's diversity. Functional regions are defined by economic and social interactions, like commuting patterns, but KMA is primarily an administrative entity. Natural regions are delineated by physical features like topography or drainage basins, not urban administrative boundaries.
Takeaway: In Indian urban geography, metropolitan planning authorities often define formal regions for infrastructure development, while functional urban regions emerge from actual economic and commuting patterns that may extend beyond administrative boundaries.