In definitions of angle pair, two given angles cannot be both? A. adjacent and vertical B. supplementary and congruent
C. adjacent and complementary
D. vertical and congruent

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A: Adjacent and vertical.

Step-by-step explanation:

When two lines intersect, vertical angles are the angles that are opposite (you can see the draw at the end) such that these two angles are only connected by the intersection point.

And two angles are adjacent if these angles are separated by one of the lines.

Then two angles can't be adjacent and vertical at the same time.

Because if two angles are adjacent, then these angles are separated by one of the lines, thus these angles can't be opposite, concluding that these angles can't be vertical angles.

And if two angles are vertical, the only "contact" point between these angles is the intersection point, then these angles can't be divided by one of the lines, then these angles can't be adjacent angles.

Then the correct option is A: adjacent and vertical.