This translation is correct because each point was translated by a vector, meaning that each point was translated in the same direction and distance. A segment that joined each point and its corresponding point on the image is parallel to the vector, proving that they are moving in the same direction. The length of a segment connecting corresponding points would also be the same length of the vector the image was translated by, proving that the point was translated the same distance. Since, translations are rigid motions, the size and shape of the image is congruent to the pre image.

Information: Translation