In order to decrease Karst topography, we should add less carbon dioxide to the atmosphere since that causes the rainwater to become acidic.
Carbon dioxide in small quantities cannot cause too much acid rain but with the increase in its emissions, a situation has formed where acid rain instances have risen.
This leads to the acid rain dissolving limestone which causes Karst topography. Reducing carbon dioxide would therefore decrease this phenomenon.
In conclusion, option A is correct.
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