I believe you are talking about the Sergei in the “What, of This
Goldfish, Would You Wish?” If that's so, then the theme about happiness presented here is that people hold onto different things for their happiness. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help.
This question could go either way. A hero is just a person "idolized for being courageous". This could mean a role model, or successful person, or even a super hero. If you are talking about a super hero, technically they don't have responsibilities because they are not required to use their powers to help anyone.
I think it would be D
Hope this helps!
STSN