In the following question, the sentence is given with a blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by selecting the appropriate option. The detective's ability to ________ makes it easy for him to scare suspects into confessing.

Introduction / Context:
This English sentence completion question tests vocabulary, collocation, and understanding of meaning in context. The sentence describes a detective whose special ability helps him scare suspects into confessing. We have to find the word that correctly completes the phrase ability to ________ so that the whole sentence makes sense in standard English and reflects a realistic investigative technique.

Given Data / Assumptions:

• The subject is a detective, a professional who questions suspects.
• The clause makes it easy for him to scare suspects into confessing indicates psychological pressure rather than physical force.
• The detective has an ability, which is likely a skill or technique used in conversation.
• The blank follows the infinitive marker to, so a verb in base form is required.
• We assume the correct word should describe tricking or deceiving suspects in some way.

Concept / Approach:
The grammatical requirement is to choose a verb that can follow to and that semantically explains how the detective can frighten suspects into revealing the truth. In investigative contexts, a common strategy is to bluff, meaning to pretend to have more evidence or power than one really has, in order to pressure suspects. The other options either do not fit the context or are not used as suitable verbs in such a phrase. This question therefore checks knowledge of the verb bluff and its association with interrogation techniques.

Step-by-Step Solution:
Step 1: Recognise that ability to must be followed by a verb describing a skill. Step 2: Consider bluff, which means to pretend, to deceive someone by making them think you know more than you do. Step 3: Check if this meaning suits the context. A detective can bluff about having strong evidence to scare suspects into confessing, so it fits perfectly. Step 4: Evaluate stuff. As a verb, stuff usually refers to filling something with material, which does not relate to questioning suspects. Step 5: Enough is an adjective or adverb, not a verb that can directly follow to in this meaning. Step 6: Cough is a verb describing a physical reflex of the throat and has no logical link to scaring suspects into confession in this sentence. Step 7: Scoff means to mock, but ability to scoff would mean the detective mocks people, which does not clearly explain making suspects confess through fear or trickery. Step 8: Conclude that bluff is the only word that is both grammatically correct and contextually appropriate.

Verification / Alternative check:
Substitute bluff into the sentence. The detective ability to bluff makes it easy for him to scare suspects into confessing reads naturally and clearly implies that he pretends to have stronger evidence or knowledge. Trying to insert stuff, enough, cough, or scoff makes the sentence sound awkward or meaningless. This test reinforces that bluff is the correct option.

Why Other Options Are Wrong:
Stuff is wrong because it refers to filling physical objects and does not describe an interrogation skill. Enough is not a verb and cannot be used grammatically after to in this way. Cough refers to a physical action and has no realistic connection to making suspects confess in a typical investigation narrative. Scoff, while it is a verb, means to mock, and ability to scoff would suggest a rude attitude rather than a strategic method of extracting confessions. None of these meanings align with the idea of using psychological deception in questioning.

Common Pitfalls:
Students sometimes focus only on rhyme or sound, especially when all the options share similar endings. This can tempt them to pick a word that fits the rhyme pattern but not the meaning. Another pitfall is ignoring the subject, in this case a detective, and not asking what realistic skill such a person would rely on. Always consider both grammar and real world sense when completing sentences in exam questions.

Final Answer:
The correct answer is bluff.