The correct option is B.
In the question given above, you are to develop an essay that is in favor of vegetable farming. The two objects that are been compared here are vegetables and lawns. Thus, any resource that will be used in supporting your argument must be one that deals with the relationships, benefits and the demerits that exist between keeping a front lawn and keeping a vegetable garden. Looking at all the options given above, it is only option B that expresses the relationship between the two.
I don't have the book so I can't give a line of evidence but Atticus was all about teaching Jem and Scout those little life lessons without them even noticing so this instance was one of those little lessons he gives them. Hope this helps :)
