Question

the mood of a story is the
main feeling expressed by the central character.
emotion or atmosphere created by the author.
happiness felt by readers as conflict is solved.
struggle between two forces or characters.

Explanation:

The mood of a story is about the overall emotion or atmosphere that the author constructs. It's not just the central character's feeling (as that's more about character's emotion), nor is it only the happiness at conflict resolution (mood can be various emotions like sadness, suspense etc. throughout the story), and the struggle between forces/characters is plot - related (conflict).

Answer:

emotion or atmosphere created by the author.