The highly polished monolithic Ashokan Pillars were carved out of single pieces of buff-colored sandstone. These sandstones were typically sourced from quarries located near specific regions. The correct answer is option 1, which states that the sandstone for the Ashokan Pillars was usually mined from the quarries of Chunar near Mirzapur.

Option 2, Lauriya in Nandangarh, is incorrect as it does not mention the buff-colored sandstone used for the pillars.

Option 3, Samath near Varanasi, is also incorrect as it does not mention the buff-colored sandstone used for the pillars.

Option 4, Udayagiri near Bhubaneswar, is incorrect as it does not mention the buff-colored sandstone used for the pillars.

It is important to note that the Ashokan Pillars were carved out of single pieces of buff-colored sandstone, and the quarries at Chunar near Mirzapur were a common source for this specific type of sandstone.