Step-by-step explanation:
Very quick and effortless example of vertical angles in the attached image. When 2 straight lines intersect, the 2 angles opposite each other at that point are vertical angles, and they are always congruent.
I'd say it's the 3rd option:
"Vertical angles are a pair of non-adjacent angles formed by two intersecting lines."
but any of the first three could be technically true really. Adjacent angles are 2 angles that share a side, and vertical angles cannot share one.
