Final answer:
The best fit for the sentence is 'B. reprimanded', as it correctly implies that the teacher scolded the boy for his misconduct of putting slime in his partner's hair.
Step-by-step explanation:
The correct answer to the question is 'B. reprimanded'. The sentence suggests that the first-grade teacher is taking disciplinary action against the boy for a specific misconduct, which is putting slime in his spelling partner's hair. The word 'reprimanded' fits best in this context, as it means to scold, chastise, or rebuke someone, especially in a formal way due to their behavior. The other options do not appropriately convey the needed disciplinary context. The verb 'contorted' (A) typically relates to twisting or bending something out of its normal shape. 'Irked' (C) suggests annoyance but does not carry the formal disciplinary connotation. 'Reassured' (D) means to restore confidence to someone, which is not relevant in this context.