You are given that all three sides of both the triangles are "approximately equal"
This means the answer is D. SSS (Side-Side-Side)
It can't be A. because S-A-S means side-angle-side and these are not the "givens"
It can't be B. because A-S-A means angle-side-angle and these are not the "givens"
It can't be C. because A-A-A means angle-angle-angle and these are not the "givens"
Hope this helped!
~Just a girl in love with Shawn Mendes