A figure only becomes bigger if it is dilated. This figure is reflected, not dilated, so A is not the answer.
Shapes are similar if the ratios of their corresponding side lengths match. Basically, they are the same shape but can be in a different size or direction. In our case each side is the same length, and they are both triangles. Therefore these shapes ARE similar, so be could be the answer.
If you were to rotate the two triangles and look at the angles that were in the same spot, those are corresponding angles. They would have the same angle measure. If you were to turn each triangle tip pointing up, (S,R') would have the same angle measure, along with (R, S') and (T,T'). As you can see, R is equal to S', so C could also be the answer.
In D we can see that R corresponds to S', not T, so D is not the answer.
Now we are torn in between B and C. C is just explaining one angle. B is saying that the shapes are similar. This would mean that all of their corresponding angles. C is just an example of B. B has it all in one. Therefore, our answer is B) <span>Figure RST is similar to figure R′S′T′.
