Answer:
a. right angles.
Explanation:
Perpendicular lines intersect and form 4 right angles.
When two perpendicular lines intersect, you can assume the shape of '+'
We can see that there are 4 right angles made in this shape.
Moreover a straight line is 180 degrees, when it is divided into two equal parts during perpendicular bisection, two right angles are formed. Similarly two right angles are formed on the other side of the line.