According to the problem, the transformation is a translation.
It is important to know that translations are rigid transformations, which means the figures won't change their shape or size. In other words, the images are congruent to the pre-images.
Hence, triangle C is congruent to triangle C', triangle D is congruent to triangle D', but the figures are not congruent because their shape is different.
Therefore, the right answers are B, C, and D.