The correct answer is:
A circle will maintain its shape no matter what transformations are applied to it.
Step-by-step explanation:
A "rigid" transformation is a transformation that preserves congruence. This means that the image after the transformation is congruent to the pre-image; it is the same size and the same shape, not distorted.
Any rigid transformations applied to a circle will result in that circle being congruent to itself.