The best answer would be Letter B - to entertain.
The author merely would like to provide amusement to the readers at his expense. It certainly does not persuade, explain, nor inform anything since it states - <span>But why bother with the descriptions; you’ve probably already grasped the idea!</span> - which could be taken as a witticism.
The "universal truths" best supported by the ideas and events in "The Happy Mantoo" is too much of a good thing can make a person sick. Option C is correct.
A universal truth refers to a truth that is discernible by anyone or anything in any context. It is a truth aknowledged and embraced by everybody.
For instance, happiness and love can be considered universal truths.
And the story the Happy Man digs deeper about what makes happy a human being and other universal truths.