I found the missing choices. These are:
They are skew and will never intersect.
They are parallel and will never intersect.
They are perpendicular and will intersect.
They will intersect at two points.
My answer: They are skew and will never intersect.
Lines a and b are skew lines because they are not parallel and they do not intersect. The reason that they do not intersect is because each line is in a parallel plane. Parallel means going to the same direction but neither converging nor diverging.