Which is required for karst topography to form?

The correct answer fro above statement is:

Karst topography is produced by synthetic weathering and attacks the underlying carbonate rock (limestone or dolomite). This happens below special drainage requirements. Lightly acidic water (carbonic acid in solution) is the current agent. Karst is a topography made from the release of dissoluble rocks such as limestone, dolomite, and gypsum.

answer called a epicycle;