What is one difference between a rigid and a non-rigid transformation

A. An rigid transformation is always with a square or triangle.
B. A dilation is a type of rigid transformation
C. In an rigid, the pre image and new image are congruent and the size does not change.
D. Non-rigid transformations cannot be done with closed shapes

C. In a rigid transformation, the pre-image and new image are congruent and the size does not change.