Answer:
Option a.
Explanation:
Two figures are similar if they have the same shape, but maybe different sizes, so if we have a triangle, and we dilate/contract it with a scale factor K, the original triangle and the dilated/contracted one will be similar.
Two figures are congruent if they have the same shape and size. For example, transformations that do not change the size will make congruent figures, those transformations are reflections, rotations and translations.
Now we need to find a sequence of transformations that would result in the two triangles being similar but no congruent, then we need to find the sequence of transformations that has a dilation/contraction in it.
The only sequence that has a dilation is the first one:
a) Rotation 90° centered about the origin, followed by a dilation of scale factor 3 centered about the origin.
Then option a is the correct one.