Which one of the following karst landforms is the laigest in size ?

Karst landforms follow a size hierarchy based on the coalescence of smaller features into larger ones. Sinkholes (or dolines) are small to medium-sized funnel-shaped depressions formed by chemical weathering. When several sinkholes or dolines merge, they form a larger, elongated depression known as an uvala, which can reach a kilometer in diameter [2]. The largest of all karst depressions is the polje. Poljes are massive, steep-walled, and flat-floored basins that can cover areas ranging from 5 to 400 square kilometers [3]. They often form through a combination of tectonic faulting and the coalescence of multiple uvalas or sinkholes [2]. While swallow holes are merely small openings where surface water disappears underground, poljes represent the most extensive surface features in karst topography [1].

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 8: Limestone and Chalk Landforms > Characteristic Features of a Karst Region > p. 78
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 17: Major Landforms and Cycle of Erosion > Polje/Blind Valley > p. 228
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 17: Major Landforms and Cycle of Erosion > Sinkhole/Swallow Hole > p. 227