The clockwise sequence of vertices MNO is the opposite of the counterclockwise sequence of vertices M'N'O', so it seems some sort of reflection is involved.
Length NO is 3 times length N'O', but length NM is only 7/3 times length N'M', so the figures are <em>not similar</em>. (The ratios of side lengths must be the same for the figures to be similar.)
___
Choice D includes only rigid transformations that would ensure congruence. Similar figures may also differ by a dilation factor, so C is the better choice.
