Consider △RST and △RYX. If the triangles are similar, which must be true?

a. RY/YS=RX/XT=XY/TSB. RY/RS=RX/RT=XY/TSC. RY/RS=RX/RT=RS/RYD. RY/RX=RS/RT=XY/TS

Triangles, or in any other polygon or solids, can only be considered similar if an only if the corresponding sides have the same ratio and the corresponding angles are congruent. With this concept, the answer to this item would be the second choice, B.