The standard for of this equation is x – y = 0
Firstly, options A and D are not in standard form, so they are not options.
To decided between B and C, we choose a point on the line and see if it works. For example, we'll use (2, 2).
x – y = 0
2 - 2 = 0
0 = 0
This is true for option C. Therefore, it is correct.