New SAT Math Section: Comparing Equation of Line to Graph

Question

This is a math question on a practice test for the New SAT that will come out in March. These questions should not go above the level of precalc. I'm posting a picture of the problem as well because it's a graph related question. I'm unsure about how to go about solving the problem. The equation of the line seems close to point-slope form but it isn't exactly.

Question: If $0<c<1$, which of these could be the graph of $y-x=c(x+y)$ in the $xy$-coordinate plane?

The Graphs for the problem

Answer 1

Hint:

$$y-x = c(x+y) \Rightarrow y = \bigg(\frac{1+c}{1-c}\bigg)x$$

And $d$ is the only graph with a positive gradient.