In English idioms and phrases, choose the correct meaning of the expression to burn the midnight oil.

Introduction / Context:
This question tests your knowledge of the idiom to burn the midnight oil. Idioms enrich language by expressing ideas in colourful and compact ways. The phrase comes from a time when people used oil lamps for light while studying or working at night. Modern exams include such idioms to see if candidates understand and can interpret figurative expressions commonly used in spoken and written English.

Given Data / Assumptions:

The idiom presented is to burn the midnight oil.
The options describe different possible interpretations about resources, lamps, and work habits.
Only one option correctly captures the widely accepted idiomatic meaning.

Concept / Approach:
To burn the midnight oil means to stay up very late in the night in order to study, read, or work on some task. The focus is on the long hours and effort put in beyond normal time, not on wasting or saving resources. Historically, burning oil at midnight implied that a person was working so late that the lamp oil was being used during hours when most people would sleep. Therefore, the meaning centres around late night hard work or study rather than literal burning or any idea of conservation.

Step-by-Step Solution:
Step 1: Think of common sentences you have heard, such as She burnt the midnight oil before the exam or They are burning the midnight oil to complete the project. Step 2: Notice that in these examples, the phrase always refers to people staying awake and working into the late hours. Step 3: Compare this concept with option B To read or work late into the night, which exactly reflects this idea. Step 4: Check option A When resources get finished half way, which focuses on resource depletion and not on working late. Step 5: Check options C and D, which talk about the value of a lamp or saving resources, and see that they do not describe the context of long hours of work.

Verification / Alternative check:
You can test the options by inserting them into a sentence. For example, Rahul has been burning the midnight oil to prepare for his engineering entrance exam. Replacing the idiom with option B gives Rahul has been reading or working late into the night to prepare, which clearly fits the context. Substituting any of the other options leads to sentences that feel unnatural or do not describe exam preparation accurately. Additionally, standard dictionaries and English usage guides confirm that the idiom means working or studying late into the night, not anything about resource saving or lamp value.

Why Other Options Are Wrong:
Option A suggests that resources are finished halfway, which introduces an idea of failure or shortage that is not present in the idiom. Option C speaks about the value of a small lamp being greatest in darkness, which sounds like a proverb but does not match the established meaning of the idiom. Option D To save some resources for the future is closer to the idea of conservation and planning, which is unrelated to staying awake and working late at night.

Common Pitfalls:
Students sometimes confuse idioms with proverbs or treat them as literal statements about physical objects, such as oil and lamps. This leads them to choose answers related to saving or wasting oil rather than understanding the figurative sense of effort and time. Another pitfall is to overthink the imagery and invent meanings that are not recognised in standard English. Regular reading of newspapers, novels, and high quality articles helps to fix idiomatic meanings through repeated exposure in natural contexts.

Final Answer:
To read or work late into the night