The theme in a story is its underlying message, or 'big idea.' In other words, what critical belief about life is the author trying to say without actually coming right out and saying it in the writing of a novel, play, short story or poem?
Building a fire is an act of technical skill and technology, and fire in literature has also often been used as a symbol of knowledge. The building of a fire thus symbolizes life in the story, but also life through human knowledge, skill, and technology.
B. A possessive pronoun shows ownership, I.e. Mine, yours, hers, theirs, his