Answer: Yes, triangle ABC is congruent to triangle A′B′C′, because a reflection is a rigid transformation. A rigid transformation is a transformation that preserves .the size and shape of a figure, meaning that the corresponding sides and angles of the figure are congruent after the transformation. A reflection is a transformation that flips a figure over a line of symmetry, creating a mirror image. In this case, triangle ABC is reflected over the x-axis to produce triangle A′B′C′. The two triangles have the same side lengths and angle measures, so they are congruent by the SSS (Side-Side-Side) criterion.