The answer is the last choice. It says the triangle is dilated by a scale factor of 

. To check this we can just look at the side lengths if the triangles. 

 has a length of 8 by looking at the graph, and 

 has a length of 2 from the graph too. So when we put those lengths

 into a fraction, it simplifies to 

. The only answer that says this is the last answer choice.