Given that triangle NLM is reflected over the line segment as shown, forming triangle ABC.
When a point is refrected across a line, the relative distance form the point to the line of refrection is preserved. That is the distance from the point to the line of refrection is equal to the distance of the image to the line of refrection.
Thus, from the figure, it can be seen the point B is of the same distance to the line of refrection as point M, so is point A to point L and point C to point N.
Thus, ΔNLM is similar to ΔCAB
Therefore, the congruency statement that is correct is ΔNLM ≅ ΔCAB