Question

In which diagram are angles 1 and 2 vertical angles?

2 lines intersect and form 4 angles. Labeled clockwise from the top: blank, 2, blank, 1.
3 lines extend from a point and form 2 angles, labeled 1 and 2. Both angles add up to 90 degrees.
A horizontal line has 2 lines extending from a midpoint forming 3 angles. Labeled from left to right: 1, 2, 3.
A horizontal line intersect with another line forming 4 angles. Labeled clockwise from top-left: 1, 2, blank, blank.

Answer 1

The first diagram. When two lines intersect, vertical angles are the opposite (non-adjacent) angles. In the first picture 1 and 2 are opposite each other, so they are vertical angles.