Final answer:
Sentence C - 'One noise, then another, a quick series of frantic noises - suddenly broke in on the silence.' creates a nervous mood.
Step-by-step explanation:
The sentence that most clearly creates a nervous mood is sentence C: 'One noise, then another, a quick series of frantic noises - suddenly broke in on the silence.'
This sentence uses words like 'frantic' and 'suddenly' to evoke a sense of anxiety and unease, creating a nervous mood.
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