Answer: x=7 is the line parallel to the given line x=8 .
Explanation:
Parallel lines are the lines which are always same distance apart and never intersect. The given line is x=8 with intersects the x axis at x=8 and it is parallel to y axis with slope infinite or not defined. So from the given options only x=7 is the line which is equidistant(same distance between them at any point) never intersect x=8 and is parallel to y - axis. Therefore x=7 is to line which is parallel to x=8.