Answer: D) The author can reveal hidden meanings about the monster by using words with strong connotations.
A connotation is a secondary meaning of a word which is different from its dictionary meaning (called denotation). It is useful for the characterization of monsters, as it gives words more varied meanings and therefore allows a richer characterization.
Whether the author employs language effectively or not, the reader always needs to use his or her imagination. Moreover, language has no impact on whether the monster is revealed early or late in the story. Finally, the plot can indeed be steered in unexpected directions through language. However, this has nothing to do with the characterization of monsters.