It’s like acting without thinking or acting in a horrible
Considering that tone is the speaker´s attitude towards a certain situation and consequently it expresses a specific emotion (mood and meaning). In this case, we can infer that the person feels dissapointed, sad and perhaps a little bit upset. He or she would "say with expression" option C. test, hard. (In fact I would emphasize believe and test in the first sentence and hard in the second).
the attitude that the author or narrator has toward the subject ...
Your subject is teacher
I believe the complete subject is new chemistry teacher
