Tone in rhetoric is how your writing is conveyed. The type of attitude that you portray. Rhetoric contains many devices such as foreshadowing, flashback, repetition, etc. Tone can be considered one of those devices as it can sway the reader and the writer can use it as what is called a 'Rhetorical strategy' to influence the reader.
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The answer is A because direct objects can only follow a transitive verb and predicate nominatives can only follow linking verbs.
