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

The Rann of Kutch is the best example of land formed by repeated sea level falls, resulting in extensive marshland.

Historically, the area was a shallow part of the Arabian Sea. A geological shift cut off its connection to the sea.

Over time, this region transformed into a seasonal marshy salt desert.

During the monsoon season, the marsh fills with water, stretching from the Gulf of Kutch in the west to the Gulf of Cambay in the east.

In the summers, the water evaporates, leaving behind a white, salty crust.

Hence option (d) is the correct answer.