The correct option is C 2{7+2(6+5+4+3+2+1)}64C2
In a 8*8 square, there are 7*7 squares on the inside which can have a corner common with another one. For each such corner, the squares may be selected in 2 ways (along either diagonal direction).
Hence, probability =2∗(7∗7)64C2=9864C2
This matches with option (c).
(Note: in the options, they have selected 2 consecutive squares diagonally. There are 2 major diagonals with 8 squares and 4 minor diagonals with 7,6,5,4,3,2 squares. Hence, the form given)