In this question, choose the option that best expresses the meaning of the common English idiom "pull the plug" as it is used to describe stopping an activity, service, or project.

Introduction / Context:
The expression "pull the plug" is a widely used English idiom, especially in discussions about projects, services, funding, or ongoing activities. The aim of this question is to test your understanding of idiomatic usage, which is very important for competitive exams and real life communication. Idioms rarely mean exactly what the individual words suggest; instead they carry a figurative, established meaning in common usage. Understanding this idiom helps you read editorials, policy discussions, and workplace emails with better accuracy.

Given Data / Assumptions:

The idiom under discussion is "pull the plug".
The context usually involves an activity, plan, project, or service that is already in progress.
You must choose the option that best matches the figurative meaning in standard English usage.
We assume no medical life support context is being tested here, only general idiomatic meaning in public discourse.
Only one option accurately captures the accepted sense of the idiom.

Concept / Approach:
To solve idiom questions, you should recall how the phrase is used in newspapers, books, and conversations. The literal picture behind "pull the plug" is of cutting off power or a supply by removing a plug from its socket. Figuratively, it refers to ending or terminating something by cutting off support, permission, or funding. So the core idea is stopping continuation, not saving, refusing once, or simply wasting work. You should match this core sense to the closest given option and reject choices that add meanings like last minute rescue or simple refusal, because they do not reflect how native speakers actually use this idiom.

Step-by-Step Solution:
Step 1: Recall or infer the figurative image of pulling a plug from a socket and stopping the power or flow. Step 2: Map this image to real life situations: ending a project, cancelling a plan, or stopping a service by withdrawing support or permission. Step 3: Evaluate option A, "Make a firm refusal in a particular situation". A firm refusal is a single act of saying no, not necessarily stopping an ongoing process, so this is not accurate. Step 4: Evaluate option B, "Save a situation by acting at the last possible moment". This is closer to the idiom "save the day" or "step in at the last minute", which is the opposite of stopping something. Step 5: Evaluate option C, "Waste the efforts that somebody has already put in". While ending a project may result in wasted effort, the idiom focuses on the act of stopping, not on the emotional result of waste, so this is not the primary meaning. Step 6: Evaluate option D, "Prevent an activity, service, or project from continuing any further". This directly expresses the core idea of stopping continuation, and therefore matches the idiom perfectly.

Verification / Alternative check:
You can verify your answer by recalling common sentences from newspapers or business reports, such as "The government decided to pull the plug on the subsidy scheme" or "Investors pulled the plug on the failing start up". In each case, the writer means that support was stopped and the activity could no longer continue. No sense of last minute rescue or simple refusal is implied. This confirms that the idiom focuses on termination of an ongoing plan or service.

Why Other Options Are Wrong:
Option A is wrong because a firm refusal can occur before something begins and does not imply stopping an existing activity.
Option B is wrong because it suggests rescue at the last minute, which is the opposite of shutting something down.
Option C is wrong because it focuses on wasted effort, which may be a side effect but not the essential meaning of the idiom.

Common Pitfalls:
Students sometimes over focus on the emotional tone of an idiom and confuse it with other expressions. Another common mistake is linking "pull the plug" only with medical life support machines and thinking it always means ending a life. In many everyday contexts, especially exam passages, the idiom simply refers to cancelling or terminating a plan, policy, or project. Always pay attention to the broader sentence to decide whether the figurative meaning is about stopping continuation rather than saving or refusing.

Final Answer:
Prevent an activity, service, or project from continuing any further