The answer is D.
When you rotate a plane around its center with its angle of rotational symmetry, it will map onto itself.
In this example, we have a regular hexagon which has 6 axes of symmetry.
To find its angle of rotational symmetry, we need to divide 360 by its number of AoS.
In this example, 360 / 6 = 60 degrees is the angle of rotational symmetry.
Since 90 is not a multiple of 60, we will eliminate choices A and B.
In C it says "reflect across the line x = -5" which isn't an AoS of the hexagon.
Lastly, in D, we need to "rotate 120 (which is a multiple of 60)", and "reflect across x = -7 (which is an AoS of the regular hexagon)". And it maps onto itself.