Question

triangle def is congruent to △def by the sss theorem. which single rigid transformation is required to map △def onto △def? dilation reflection rotation translation

Explanation:

Dilation is not a rigid - transformation as it changes the size. Reflection flips a figure over a line. Rotation turns a figure around a point. Translation slides a figure. Since the two triangles are congruent by SSS and have a mirror - like orientation, a reflection is required to map one onto the other.

Answer:

B. reflection