Short answers, pulled from the story.
KARST stood for Kilometer-square Area Radio Synthesis Telescope, a Chinese proposal put forward during the 1990s to host the international Square Kilometre Array. It called for roughly 30 individual radio dishes, each about 200 meters in diameter, placed in the natural limestone depressions of China's southwestern provinces.
KARST was planned for the karst landscape of China's southwestern provinces, with Pingtang County in Guizhou Province as a primary focus. A site survey identified 288 suitable locations in that county alone.
After site evaluation surveys, both Argentina and China were dropped from the SKA competition, leaving South Africa and Australia as the two shortlisted candidates. On the 25th of May 2012, the SKA was announced as a split array across the South African and Australian sites.
KARST would have consisted of about 30 individual elements, each roughly 200 meters in diameter. Together they would have provided approximately one square kilometre of radio collecting area.
Chinese astronomers did preliminary work on FAST as a prototype for KARST. FAST was ultimately built in a single karst depression in Pingtang County, Guizhou Province, the same region where the 288-site survey for KARST was conducted.
A site survey of 288 suitable locations was performed in Pingtang County, Guizhou Province, as part of the planning for the KARST proposal.