Where in the passage do you get to find an example of 'one good turn deserves another'?

Directions: Read the following passage and answer the question that follows.

A young fisherman frees a huge bird from a net and in return the bird showed him a better place for fishing, where the fisherman catches a fish with gold and silver scales.
The young lad takes the fish to the king asking for his daughter’s hand in return. The princess agrees to marry the fisherman on one condition that he provides her with a key to wish house.
The lad took a lot of pains to search miles from one continent to another for the wish key, however did not find one.
He then made a whistle of a key and blew on it, he returned back to his hometown as an achiever, making all believe that he had the wish key, and demanded royalty lifestyle from king, which were fulfilled.
The princess understood what the lad was doing and could see through the cleverness of the lad, ultimately agreeing to marry the fisherman.