This is my sisters SATS question in her preparation book however the top box doesn't make sense as it says that "for singular and plural nouns that DON'T end in an S and apostrophe s" however the example shows the word bus's.this ends In s?! Is this a mistake or is this some sort of exception?
many thanks!

Match each excerpt to the correct stanza structure. 1. it was many and many a year ago, in a kingdom by the sea, that a maiden there lived whom you may know by the name of annabel lee; and this maiden she lived with no other thought than to love and be loved by me. (from "annabel lee" by edgar allan poe) 2. o thou, new-year, delaying long, delayest the sorrow in my blood, that longs to burst a frozen bud and flood a fresher throat with song. (from "in memoriam" by alfred lord tennyson) 3. nature’s first green is gold, her hardest hue to hold. her early leaf’s a flower but only so an hour. then leaf subsides to leaf. so eden sank to grief,; so dawn goes down to day. nothing gold can stay. (from "nothing gold can stay" by robert frost) 4. at sestos hero dwelt; hero the fair, whom young apollo courted for her hair, and offered as a dower his burning throne, where she should sit for men to gaze upon. the outside of her garments were of lawn, the lining purple silk, with gilt stars drawn; (from "hero and leander" by christopher marlowe) quatrain couplet octave sestet