ANSWER
D. rotation, translation, reflection
Step-by-step explanation
Dilation is not a rigid motion.
When the triangle is dilated the image triangle may become bigger ( magnification) or smaller (reduction).
When the scale factor is negative 1, a congruent triangle is obtained.
Hence dilation will not always produce a congruent triangle.
Rotation, reflection and translation are rigid motions and hence will always produce a congruent triangle.