The question below consists of a set of labelled sentence parts. Out of the four options given, select the most logical order of the parts X, Y and Z so that they form a coherent sentence. We have seen that, when X - think of it as losing its parts and shrivelling to a point Y - occupy any portion of space, we need not Z - we deny that a mental image can.

Introduction / Context:
This is a sentence reordering question where the middle segments of a sentence, labelled X, Y, and Z, have been jumbled. The learner must choose the correct sequence that produces a clear and meaningful philosophical statement about mental images and space. Such questions test logical flow, grammar, and ability to understand complex abstract sentences.

Given Data / Assumptions:
- Introductory part: “We have seen that, when”- Segment X: “think of it as losing its parts and shrivelling to a point”- Segment Y: “occupy any portion of space, we need not”- Segment Z: “we deny that a mental image can”- The tail of the sentence is implied by combining these segments correctly.

Concept / Approach:
We are dealing with a complex sentence that likely has a clause like “when we deny that a mental image can occupy any portion of space, we need not think of it as losing its parts and shrivelling to a point.” The structure involves a “when” clause followed by a main clause beginning with “we need not.” We must therefore arrange Z, Y, and X so that “when” is followed by a complete clause and “we need not” appears before the final action “think of it as losing its parts and shrivelling to a point.”

Step-by-Step Solution:
Start with the phrase “We have seen that, when.” After “when,” we normally expect a subject and verb. Among the segments X, Y, and Z, only segment Z begins with a clear subject “we,” making “we deny that a mental image can” a natural beginning for the “when” clause.Thus, Z should come first, giving “We have seen that, when we deny that a mental image can ...” This sets up what we are assuming about mental images.Next, we must indicate what this mental image cannot do. Segment Y continues “occupy any portion of space, we need not,” which pairs neatly with “we deny that a mental image can occupy any portion of space.” At the same time, it also leads into the main clause “we need not ...”So we place Y after Z, forming “we deny that a mental image can occupy any portion of space, we need not ...”The remaining idea is in X: “think of it as losing its parts and shrivelling to a point.” This fits perfectly after “we need not,” producing the full meaningful sentence.Putting it together, we get: “We have seen that, when we deny that a mental image can occupy any portion of space, we need not think of it as losing its parts and shrivelling to a point.” The order of labels is Z Y X.

Verification / Alternative check:
Check whether other orders produce grammatical or logical sentences. For instance, if we started with Y after “when,” we would have “when occupy any portion of space, we need not,” which lacks a subject and is ungrammatical. If we began with X, we would get “when think of it as losing its parts,” which again lacks a subject and is incomplete. Only starting with Z provides a full clause with subject and verb. Moreover, X must follow “we need not” because it is the action that we need not perform. Therefore, ZYX is the only order that yields a coherent, grammatically sound sentence.

Why Other Options Are Wrong:
Option ZXY places X after Z, giving “when we deny that a mental image can think of it as losing its parts,” which changes meaning and disrupts grammatical roles.Option YZX begins with Y, resulting in “when occupy any portion of space,” which is ungrammatical due to missing subject.Option YXZ has the same subject problem and also misplaces “we need not,” which must come before X to make sense.

Common Pitfalls:
Learners may try to follow the physical order X Y Z without checking for subject verb agreement and the logical role of “we need not.” Another trap is to ignore the clause structure around “when,” which almost always introduces a clause that requires a subject and a verb. Noticing that only Z begins with “we” is a big clue.

Final Answer:
The most logical and grammatically correct order of the parts is ZYX.