The Axis of symmetry is the line that goes through the center of the parabola. And resembles a symmetrical shape that makes the parabola look the same on both sides.
In this case for A, -1.5 would be the answer because it is in the center of the parabola on the x-axis. For B, 2 is the axis of symmetry because it lines up in the center of the parabola.
