Final answer:
The hypothesis of the conditional statement is that two angles are vertical angles, because vertical angles are always congruent.
Step-by-step explanation:
To understand this, we need to know that vertical angles are formed when two lines intersect. The angles opposite each other are called vertical angles. Vertical angles are always congruent, which means they have the same measure. Therefore, if two angles are vertical angles, it can be concluded that they are congruent.