The correct option is 2 and 3 only.
Explanation
Groundwater acts as a significant geomorphic agent primarily through chemical processes rather than mechanical force. This action is most pronounced in soluble rocks, leading to the formation of distinct landforms known as Karst topography.
Statement 1 is Incorrect. The physical or mechanical removal of materials by moving groundwater is insignificant in developing landforms because the velocity of groundwater flow is generally very low. Instead, the chemical action (dissolution and solution) is the dominant factor in eroding and shaping the landscape.
Statement 2 is Correct. In rocks such as limestones or dolomites, the two primary active processes are solution (which dissolves the rock material) and precipitation (which deposits dissolved minerals). These chemical processes are responsible for creating both erosional and depositional landforms.
Statement 3 is Correct. Karst topography is specifically developed in rocks rich in calcium carbonate (limestone) or magnesium carbonate (dolomite). These rocks are chemically soluble in water containing dissolved carbon dioxide, allowing groundwater to form features like sinkholes, caves, and caverns.
Key Takeaway: Groundwater modifies landscapes primarily through chemical weathering (solution and precipitation) in soluble rocks like limestone, creating Karst topography, whereas physical erosion is negligible.