Answer:
Neutral tone, literal
Step-by-step explanation:
To have a positive tone, it has to invoke a positive or "warm" feeling when you read it. The sentence has no positive or negative feel to it, it's just a statement.
The sentence isn't referring to anything that is put in place of something else — i.e. someone talking about a bird going silent but is actually referring to a mood or feeling — it's just a plain statement without talking about anything besides what is in the statement