It would be choice "D". When you change all these equations into slope-intercept form (Y=mx+b or Y equals the slope times "X" plus the y-intercept), choice "D" is the only one with the same slope which is the the value of "m" in slope-intercept form. In this case, when both equations in choice "D" is changed to slope-intercept form, both equations' slopes become -2. When slopes of two equations are the same, the lines are parallel to each other when graphed.
