Which one of the following is the best example of repeated falls in sea level, giving rise to present-day extensive marshland?

Answer: D. The Rann of Kutch is the best example of repeated sea-level falls forming present-day marshland. The Great Rann of Kutch and Little Rann are salt marshes (about 30,000 sq km combined) in Gujarat, formed by REPEATED MARINE TRANSGRESSIONS AND REGRESSIONS over geological time. The area was a shallow sea/gulf, was uplifted with eustatic sea-level falls, and now stands as low-elevation saline marshland flooded annually during monsoon. The Rann is the world's largest salt desert. Distractors fail: (A) Bhitarkanika Mangroves (Odisha) are deltaic mangrove forests in active Brahmani-Baitarani delta, not the result of repeated sea-level falls. (B) Marakkanam Salt Pans (Tamil Nadu) are anthropogenic — man-made salt pans, not natural marshland. (C) Naupada Swamp (Andhra Pradesh) is a deltaic swamp from sediment deposition, not eustatic regression. Source: NCERT Class 11 India: Physical Environment / Geological Survey of India.