Concept:The blank must describe diction that is repetitive, dull, and tedious.
Explanation:The sentence already says his diction was “too obviously repetitive,” which suggests sameness.
“Very dull,” “quite tedious,” and “absurdity” further show that the diction lacked variety.
“Dynamic” and “vibrant” mean lively and energetic, so they are opposites of the required meaning.
“Modulated” means adjusted or varied, which also does not fit “repetitive.”
“Monotonous” means lacking in variety and becoming boring because it stays the same.
Therefore, “monotonous” correctly completes the sentence.
Answer:His diction was too
monotonous, that is, dull and repetitive.