Answer: C) reflection and dilation
Step-by-step explanation:
The transformations of translation, reflection and rotation are considered rigid motions. They keep the figure the same size just it has been shifted around in some way. In contrast, a dilation will alter the size to make it larger or smaller depending on what the scale factor is.
Only choice C has "dilation" as part of the answer, so it must be the answer. The other choices are purely rigid motions that will keep the triangle the same size and shape. In other words, the preimage and image are congruent for choices A,B, and D.