Final answer:
In Mark Twain's 'The £1,000,000 Bank-Note', the theme of naturalism is evident in the portrayal of characters as victims of fate, which reflects the naturalists' belief in the dominance of hereditary and environmental forces over individual free will.
Step-by-step explanation:
The theme of naturalism in Mark Twain's “The £1,000,000 Bank-Note” is most noticeable in B) the portrayal of characters as victims of fate. This literary approach emphasizes the influence of environmental and hereditary conditions on human destiny, aligning with the principles of naturalism where characters often find themselves at the mercy of uncontrollable and indifferent social and natural forces. Twain's narrative illustrates how the protagonist is catapulted into a series of events that are beyond his control, signifying his subjection to the whims of fate and societal dynamics. This aligns with naturalistic writers' tendencies to depict human beings as small, insignificant entities trapped by circumstances, unable to exercise free will to significantly change their predetermined outcomes.