Answer: A) The life lesson the author teaches through the story.
Explanation: In literature, the theme is the underlying message of a story, it is what critical belief about life is the author trying to convey in the writing of a novel, play, short story or poem. Usually this belief, or idea, is universal and transcends cultural barriers. So, from the given options, the one that represents the definition of theme, is the corresponding to option A: a theme is the life lesson the author teaches through the story.