Here you have four possible transformations to make:
- dilation;
- translation;
- reflection;
- rotation.
First transformation is not rigid (doesn't preserve the lengths) and last three transformations are rigid (each of them preserves the lengths of the figure).
So, the only possible answer is dilation, because from the diagram you can see that triangles KLM and K'L'M' have different dimensions (KL is less than K'L', LM is less than L'M' and KM is less than K'M').
Answer: correct choice is A.