B.) y=3x The slope of a given line is defined by <em>y=mx+b</em>, where b is the y-intercept (the point at which the line crosses the y-axis) and m is the slope (rise/run). We see that the y-intercept is 0 (because the line hits the y-axis at 0) and the slope is 3 (rise=3 and run=1, so 3/1=3).