Question 197525
The graph of {{{x=4}}} is a vertical line. So what does that tell you about the slope? Remember, ALL vertical lines have undefined slopes. So we can easily rule out choices 1) and 2). So we're only left with choices 3) and 4). Since {{{x=4}}} is a vertical line, and all vertical lines are parallel to the y-axis, this tells us that {{{x=4}}} is parallel to the y-axis.