IDIOMS — Choose the option that best expresses the meaning of the underlined phrase. Sentence: 'The teacher warned the student once and for all that no mischief shall be tolerated in the class.'

Introduction / Context:
“Once and for all” is a fixed expression used to mark a final, decisive statement that settles a matter permanently. In classroom discipline, it signals that the rule has been made clear and will not be revisited.

Given Data / Assumptions:

• Speaker: teacher; audience: student(s).
• Action: warning about mischief.
• Idiom: “once and for all” emphasizes finality and conclusiveness.

Concept / Approach:
Because the idiom encodes final resolution, the closest single-word paraphrase is “finally” or “definitively.” Tone words such as “angrily” or “coldly” describe how something is said, not its conclusive status. “Authoritatively” is about authority, which the teacher has, but it does not guarantee finality.

Step-by-Step Solution:
1) Identify the idiom and its fixed meaning.2) Separate tone from semantic content.3) Choose “finally” as the best one-word equivalent.4) Check that the paraphrase preserves the idea of a decisive end to debate.

Verification / Alternative check:
Paraphrase: “The teacher finally warned the student, making the policy permanent.” The sense of conclusiveness remains intact.

Why Other Options Are Wrong:
A) “authoritatively” — about manner, not finality.C) “angrily” — emotion, not conclusiveness.D) “coldly” — manner/temperature of tone, not finality.

Common Pitfalls:
Confusing the emotional tone of a statement with its semantic force. “Once and for all” is about decisiveness, not mood.

Final Answer:
finally