I think it’s the red line.
So you want to put the equation into y=mx+b so you would need to subtract the x to put it on the right side so then you’ll have 2y=-x+0 then divide by 2 to get the y by itself then you’ll have y=-2x+0 that means the line would be negative and the y intercept is 0 and the only line that follows that is the red line.
Hope this helped :)