Answer:
They are perpendicular to each other.
Explanation:
It is given that there is a rectangle LMNO and this rectangle is reflected over x axis and the create a new rectangle L'M'N'O'.
Now if a straight line segment is drawn joining the point M to the point M', they will form perpendicular to each other. Thus The relationship between the line segment M-M' and the x axis is perpendicularity.