Final answer:
Vertical angles are opposite angles formed by the intersection of two lines. Option B: ∠BFC and ∠DFE are vertical angles because they are positioned across from each other where two lines intersect.
Step-by-step explanation:
Vertical angles are pairs of opposite angles made by two intersecting lines. The notation ∠ is used to denote an angle. Therefore, for two angles to be vertical (also known as vertically opposite angles), they must be positioned across from each other when two lines intersect.
In the options given for pairs of angles to be vertical, we're looking for pairs that are opposite each other at the intersection of two lines. Option B: ∠BFC and ∠DFE are indeed vertical angles because they are across from each other where two lines intersect.