Bananas
The Bananas are the fourth item in the Trading Sequence of Link's Awakening. Bananas are available at Sale's Banana Shop on Toronbo Shores. Once Link receives a can of Dog Food from a Bow-Wow who lives in a side room of Madam MeowMeow's house, the can of Dog Food can then be given to Sale, who in turn gives Link one of his many bunches of bananas. The bananas then have to be given to a monkey near the moat of Kanalet Castle, who will build a bridge and leave behind a Stick.
Because the beginning sequence of Link's Awakening's trading sequence is required to be done in order to progress further in the game, later on, it is required that Link receive the bunch of bananas and trade it. The only way that Link can enter Kanalet Castle for the first time is to give the bananas to the monkey, Kiki. Afterward, it is not required that Link still trade in order to further progress in the game.