The South-Eastern part of the Bengal Delta is undergoing ________

Correct answer: Subsidence

Explanation: The correct answer is D. Subsidence. The southeastern part of the Bengal Delta, particularly the Sundarban region, is experiencing tectonic and geological subsidence, meaning a gradual sinking of the land surface. This is due to natural compaction of deltaic sediments, tectonic activities, and excessive groundwater extraction, combined with sea-level rise and frequent cyclonic activities. The subsidence is evident in coastal erosion, salinization of land, riverbank collapse, and submergence of low-lying islands. Emergence refers to land rising. Progradation means outward building of delta by sediment deposition (mostly seen in western Bengal delta).