In the following question, choose the alternative that best expresses the meaning of the English idiom/phrase "an axe to grind".

Introduction / Context:
The idiom "an axe to grind" is frequently tested in English vocabulary sections, especially in exams that focus on idioms and phrases. On the surface, it appears to refer to sharpening a tool, but in actual usage it describes a hidden or selfish motive behind someone's actions or opinions. Understanding such figurative uses of language is essential for scoring well in verbal ability questions.

Given Data / Assumptions:

• The idiom given is "an axe to grind".
• The task is to choose the option that best explains its meaning.
• All options are short, general descriptions of behaviour or motives.
• Standard modern English usage and dictionary meaning are assumed.

Concept / Approach:
Historically, the idiom comes from the image of a person pretending to be interested in the welfare of others, while actually wanting to use their grinding wheel to sharpen his own axe. Figuratively, if someone "has an axe to grind", they have a personal, often selfish interest in a matter, usually not openly declared. The correct meaning therefore connects directly with "selfish motive" rather than bravery, foolishness, risk-taking, or quarrelsomeness.

Step-by-Step Solution:
Step 1: Recall the standard meaning: "an axe to grind" = "a private or selfish purpose in mind".Step 2: Examine option A: "To act bravely". This relates to courage, which is unrelated to the idea of hidden motives.Step 3: Examine option B: "To act like a fool". This suggests foolish behaviour, but the idiom does not refer to intelligence; it refers to intention.Step 4: Examine option C: "To have a selfish motive". This perfectly matches the idea of having one's own interest to serve beneath the surface of words or actions.Step 5: Examine option D: "To take risk". Risk-taking may occur with or without selfish motives and is not the core meaning here.Step 6: Examine option E: "To start an unnecessary quarrel". While people with an axe to grind might quarrel sometimes, the idiom itself focuses on motive, not on starting fights.

Verification / Alternative check:
Consider the sentence: "The journalist clearly had an axe to grind against the minister." We understand that the journalist had some personal grievance or selfish interest, not that he was brave, foolish, or simply fond of quarrelling. Replacing "an axe to grind" with "a selfish motive" preserves the meaning, while replacing it with any other option distorts it. Thus, option C is confirmed as correct.

Why Other Options Are Wrong:
"To act bravely" describes courageous behaviour and has no connection with hidden personal interests. "To act like a fool" focuses on lack of wisdom rather than on motive. "To take risk" refers to dangerous decisions, which can be unselfish as well, so it does not capture the idiom. "To start an unnecessary quarrel" is about conflict, not about underlying purpose. None of these alternatives match the standard idiomatic meaning.

Common Pitfalls:
Students sometimes confuse "an axe to grind" with idioms about quarrels or revenge because of the physical image of an axe. Another trap is assuming that it must refer to violent or risky behaviour. The safest approach is to connect the idiom with its core idea: a hidden, usually selfish agenda. Whenever you see this idiom in reading comprehension, ask yourself, "What private benefit does this person want?" That question will naturally point you to the idea of selfish motive.

Final Answer:
The idiom "an axe to grind" means to have a selfish motive.