Mangrove forests in Sundarbans develop due to which condition?

Correct answer: Tidal marshy delta conditions

The direct answer is A, tidal marshy delta conditions. The Sundarbans lies in the Ganga–Brahmaputra–Meghna delta, where river sediments create low, wet land and tides regularly bring salty water. Mangrove plants are specially adapted to waterlogged, muddy and saline conditions. Step by step: rivers build a delta; tides flood channels and marshes; soil remains wet and often salty; mangroves survive there with special roots. Option A is correct because it gives the exact physical setting. Option B, a cold dry desert, lacks the wet tidal environment. Option C, lava flow, is volcanic material and does not describe the Sundarbans. Option D, a glacial valley, is a cold mountain landform, not a tropical delta. Therefore A is the only suitable answer. Memory cue: Sundarbans = tidal delta + mangroves.