Thank you for the opportunity to help you with your question!
Two triangles are similar if they have two of their angles equal. Especially in rectangle triangles when one acute angle is equal to the corresponding of the other triangle, then the two traingles are similar.
The right answer is d.
Please let me know if you need any clarification. I'm always happy to answer your questions.
Nov 1st, 2015
A rectangle triangle is a right triangle in case you got confused,