Is this a possibly wrong answer?

This solution is only for negatively sloped lines, however positive lines can also work giving a slope of 1. Shouldnt the answer be d then?

The key is “the x intercept and y intercept are equal” so when you do slope formula for x and y that = -2 , you get a slope that is negative. For 5, the slope still turns out negative. No matter the case (or number), if both numbers for x intercept and y intercept are equal , the slope turns out negative

Oh so x=y=5 for example and not x=5, y=-5?

Yeah so you see in the picture it is written over “x intercept” a 5, same as over the “y.” So x=y=5