The best response to the above prompt is the one in option B. Generosity is about being kind, giving things or your time to others, in this option they list the actions of the players very well (while option A, C and D barely talk about it) and the rewarding feelings resulting from the acts of generosity is well expressed in Eddie words "Our clothes crusade rescues a thrift store in distress!".
B) After the teens get the idea to help the thrift store, they all work really hard to make it happen. From making pamphlets, to cleaning out their own closets, to gathering clothes from other people, they put in a lot of time and effort to bring together the donations for the thrift store. In the end, Eddie announces "Our clothes crusade rescues a thrift store in distress!" This declaration suggests that he is feeling proud of their efforts and the positive effect it had on the community. The theme is developed as the teens work together and learn the lesson the 'generosity is rewarding'.
You should be referring to the quote from "The Canterbury Tales" where the word gold is used to represent the clergy in all its purity that leaves it in such a high standard that nothing can reach it, just as gold can not be attained by rust.