Answer:
Similar polygons are polygons with the same shape, but different size:
We can discard the first pair because both triangles are from different types.
The second pair (the rectangles, top right) if they are similar, then the quotient between the lengths of the sides must be the same: 16/10 = 1.6 = 22/13.75
The triangle rectangles also are not similars, you can see that the quotient between the cathetus is different.
For the trapezoids you may see the quotients betwen base and top and the quotients between base and height.
8/5 = 1.6 = 20/12.5
8/3 = 2.66 = 20/7.5
With this information we can see that this pair may also be similar, buth the trapezoids are mirrored and not rotated (so in one the left side is angled, and in the other the right side is angled) so we can conclude that this pair is not similar.
The only right answer is the pair of rectangles.