Answer:
Graph B
This is because of the vertical line test. Say you were to draw a vertical line that stretches through the whole graph. If this line you draw passes through more than two points of the same line/function/whatever b is, it is not a function.
Angles 1 and 3, angles 2 and 4, angles 5 and 7, and angles 6 and 8. They are also congruent, because vertical angles are congruent.
True
work: f(3)=2(3)-9
f(3)=6-9
f(3)=-3
