In the following question, choose the option that best expresses the meaning of the word "REPROOF".

Introduction / Context:
This vocabulary question asks for the word that is closest in meaning to "reproof". Such questions test both your knowledge of word meanings and your ability to distinguish between similar but not identical ideas. "Reproof" is a formal noun used in English to describe blame, criticism, or an expression of disapproval when someone has done something wrong. Understanding the precise sense of the word will help you select the most accurate synonym from the options provided.

Given Data / Assumptions:
• Target word: reproof. • Reproof generally means an expression of blame, disapproval, or criticism. • Four answer choices are given: warning, ridicule, rebuke, and threat. • The task is to find the closest single word in meaning.

Concept / Approach:
To solve synonym questions, it is useful to first define the target word in simple language. Once you have a clear definition, compare it with the dictionary senses of each option. "Reproof" is almost interchangeable with "rebuke" in many sentences, both suggesting a formal or strong expression of disapproval. While warning, ridicule, and threat may involve negative attitudes, they have different focus and tone. Therefore the best synonym must share both the emotional tone and the context of correcting or expressing dissatisfaction with someone's behaviour.

Step-by-Step Solution:
1. Define "reproof" as an expression of blame or disapproval, usually spoken to someone who has done something wrong. 2. Consider "rebuke", which means a sharp or stern expression of disapproval. 3. Notice that "rebuke" can often replace "reproof" in example sentences without changing the meaning much. 4. Examine "warning", which is more about cautioning someone about possible danger or consequence, not necessarily expressing disapproval of a past action. 5. Examine "ridicule", which involves mocking or making fun of someone, usually with scorn or laughter. 6. Examine "threat", which is a statement of intention to cause harm, not simply criticism.

Verification / Alternative check:
Try using the words in the same sentence: "The teacher spoke a gentle reproof to the student." If you replace "reproof" with "rebuke", the sentence still makes sense: "The teacher spoke a gentle rebuke to the student." However, "warning", "ridicule", or "threat" would each change the meaning in an unnatural way. This replacement test is a quick way to verify that "rebuke" is the closest synonym to "reproof" in most formal contexts.

Why Other Options Are Wrong:
Option A, "warning", focuses on foretelling danger or negative consequences rather than on expressing disapproval of a completed action. Option B, "ridicule", is about mocking and can involve humour or cruelty, but it does not directly mean correction or formal criticism. Option D, "threat", suggests harm or punishment and is stronger and more aggressive than simple blame. None of these words truly capture the sense of measured disapproval that "reproof" and "rebuke" share.

Common Pitfalls:
A frequent error is to pick any negative sounding word without checking whether it matches the precise meaning of the original. Learners may also confuse ridicule with criticism because both can be negative. However, ridicule emphasises laughter and mockery, whereas reproof focuses on correction and moral or social disapproval. To avoid this, always think of a sample sentence where you know the word fits and test each option in that context before choosing your answer.

Final Answer:
The word that best expresses the meaning of "reproof" is REBUKE.