In the following passage based question, a blank has been given in the sentence: "Language, they say, is the _____ through which human beings perceive the world." Select the most appropriate word from the options to fill the blank so that the sentence becomes meaningful and maintains the metaphor of the passage.

Introduction / Context:
This question is part of a larger passage that compares language to a device which shapes how human beings see the world. The sentence uses a metaphor, and you must pick the word that best completes that metaphor. Understanding the image created by the writer is essential, because all four options are grammatically possible, but only one fits the intended comparison and flows naturally with later references to English as a lens.

Given Data / Assumptions:

• Sentence: Language, they say, is the _____ through which human beings perceive the world.
• Options: lens, resource, source, telescope.
• The same passage later speaks about English as a distorted lens for seeing animals.
• The author is using a metaphor from the world of seeing or viewing rather than from energy or finance.

Concept / Approach:
The key word in the sentence is perceive, which is closely related to seeing or sensing. When we talk about perceiving the world through something, a common metaphor is lens, meaning a medium that shapes how things appear to us. In the passage, English is later called a distorting lens for viewing animals, which clearly confirms that the controlling image is optical. Resource and source do not fit this visual metaphor as naturally, and telescope is too specific and does not match the later repeated word lens in the passage. Therefore lens is the most appropriate choice.

Step-by-Step Solution:
Step 1: Focus on perceive the world. This expression suggests seeing or experiencing reality through something that influences how it looks. Step 2: Consider lens. A lens is a part of glasses or a camera that focuses and shapes light, which makes it an excellent metaphor for language shaping perception. Step 3: Consider resource. A resource is something we use or draw upon, like money or water, which does not naturally fit the idea of perceiving the world through it. Step 4: Consider source. A source is an origin or starting point, for example the source of a river or source of information. Language can be a source of misunderstanding, but here the phrase is the through which, which favours a medium like a lens rather than an origin. Step 5: Consider telescope. A telescope is a device for viewing distant objects. While it is related to seeing, it is very specific and is not echoed later in the passage; the passage talks again about a lens, not a telescope. Step 6: Therefore lens is the only option that matches both the immediate metaphor and the later description in the passage.

Verification / Alternative check:
If you read the full passage, it goes on to say: English is perhaps the most distorting lens through which to see animals. It has perpetuated a cross eyed view of birds, beasts, fish and fowl. Because lens is repeated later, the author is clearly using a consistent metaphor. Replacing the first blank with lens keeps that consistency. If you inserted telescope, the later sentence about distorting lens would lose its echo and sound poorly constructed. This internal evidence from the passage confirms that lens is correct.

Why Other Options Are Wrong:
Resource suggests that language is a useful asset, which may be true but does not fit the phrase through which human beings perceive the world, where a medium of perception is needed rather than a utility.
Source emphasises origin rather than medium; it would be more natural in a structure like language is the source of many misunderstandings, not in the phrase through which we perceive.

Common Pitfalls:
Telescope can attract students because it is a visual instrument and seems related to perception. However, the writer wants a general term, because language affects perception of everything, not only distant objects. Moreover, good cloze test strategy is to consider the entire passage, not just the single sentence. When a later sentence repeats or extends the same metaphor, that repetition is a strong clue. Ignoring contextual clues is a common reason for mistakes in such questions.

Final Answer:
The most appropriate word is lens, so the sentence reads: Language, they say, is the lens through which human beings perceive the world.