Lets check it for 1*1 matrix.
For 1*1 matrix we have XY=YX
So, XY-YX =0
So, for 1*1 matrices there does not exist any matrix X and Y such that XY-YX = 1 (the identity matrix for 1*1 matrices)
So,the answer is 0 which is option A.
Hence option A is the correct answer.