Answer with explanation:
It is given that pair of vertical Angles are Always Supplementary.
→Vertical Angle = Angle having measure of 90°
→Supplementary = Sum of two angles is 180°.
→Sum of two vertical Angle = A supplementary Angle
→90°+90°
=180°
⇒The term which Describes a pair of vertical angles that are always supplementary=Right
Option C