Which equation represents the graph of the linear function?

Hi,
You can start by eliminating option A and B because a line is increasing if it goes up from left to right. So now the options are C and D. Then you look at the constant which is +1 or -1. This number is your y-intercept so if you look at the graph, you can see that the graph goes through the y axis at (0,-1). So the answer is D. y=3x-1.