Diagram B shows that lines a and b are parallel.
Which diagram shows that two lines are parallel?
If two lines are parallel, then the angles formed in the correspondent quadrants have the same measure.
From that, we can see that option B shows that lines a and b are parallel. This because the angle in the first second quadrant of the first intersection is 120°
The angle on the first quadrant on the second intersection is 60°
If we add these we get 180°, so its like the angles are adjacent angles, and thus, the lines are parallel