The theme that is introduced in this exposition is "Curiosity leads to dark truths."
What is a theme?
The theme basically refers to the subject or central idea of a story, article, or any writing. It can also be defined as a message the writer is trying to convey through his literature.
In the given exposition, the writer claims that starting a question is like starting a stone. The stone gets rolled from the hill and it then starts other stones and the stone then knocks to the head of a boring old bird.
With this, the writer is trying to convey that, curiosity and questioning can reveal dark truths that otherwise will be hidden.
Hence the correct option is B.
Learn more about the theme here:
https://brainly.com/question/1673952
