Final answer:
In similar trapezoids KLMN and PQRS, side NM of KLMN corresponds to side QR of PQRS because they are both non-parallel sides or legs of the trapezoids.
Step-by-step explanation:
Given that KLMN and PQRS are similar trapezoids, they have corresponding sides that are proportional in length. For trapezoids, the sides that are parallel to each other are known as the bases, and the non-parallel sides are called the legs. In similar trapezoids, each pair of corresponding sides has the same position relative to the parallel bases.
In trapezoid KLMN, side NM would correspond to the side of trapezoid PQRS that is similarly positioned. Since NM is one of the non-parallel sides or legs of the trapezoid KLMN, we need to identify the analogous leg in trapezoid PQRS. The corresponding side in PQRS to side NM is side QR, which makes option (b) Side QR the correct answer.