The sentence below consists of three labelled parts. Out of the four options given, select the most logical order of the labels to form a coherent sentence. Then there came faint rays of primrose X light that changed presently to golden Y bars, through which the dawn Z glided out across the desert.

Introduction / Context:
This question tests your ability to arrange labelled sentence fragments (X, Y, Z) in the most logical order to form a smooth, meaningful sentence. The sentence describes the gradual change of early morning light in the desert: first faint rays, then golden bars, and finally the dawn gliding out. To choose correctly, you must follow both grammatical sequence and natural visual progression.

Given Data / Assumptions:

• Base frame of the sentence: "Then there came faint rays of primrose X light that changed presently to golden Y bars, through which the dawn Z glided out across the desert."
• The labels X, Y, Z represent parts that must be attached in a logical order.
• Options describing possible orders: ZYX, XYZ, ZXY, YZX.
• We assume that the sentence should describe the colour and form of light first, then the golden bars, and finally the movement of dawn.

Concept / Approach:
The natural poetic picture is: faint rays of primrose light appear; these rays change into golden bars of light; and through those bars the dawn glides out across the desert. That sequence clearly corresponds to X (light), Y (bars), and Z (glided) in that order. Therefore, the coherent sentence will use the labels exactly as they are already positioned in the base frame: X, then Y, then Z. The other permutations would scramble this order and disrupt the flow of the description.

Step-by-Step Solution:
Step 1: Think of the visual scene being described: first there are faint rays of primrose coloured light.Step 2: Next, these rays "changed presently to golden bars", describing the transformation of colour and shape as dawn progresses.Step 3: Finally, "through which the dawn glided out across the desert" completes the image by showing the dawn itself moving.Step 4: Match these steps with the labels: X should describe "light", Y should describe "bars", and Z should describe "glided out".Step 5: The only option that preserves this order is XYZ, so option B is the correct choice.

Verification / Alternative check:
Read the sentence with the order XYZ: "Then there came faint rays of primrose light that changed presently to golden bars, through which the dawn glided out across the desert." This sentence is grammatically correct and paints a clear picture of the dawn. Try reordering as ZYX or ZXY and you would get nonsensical combinations like "primrose glided" or "the dawn light bars", which do not read smoothly or logically. Thus, XYZ is clearly superior to the other permutations.

Why Other Options Are Wrong:
Option A, ZYX, would place the "glided out" segment where the colour "primrose" should go, breaking the description. Option C, ZXY, would again start with the gliding action instead of the initial faint rays. Option D, YZX, would put "golden bars" immediately after "primrose" in a way that disrupts the "rays of primrose light" phrase and damages the structure "bars, through which the dawn glided". None of these options produce a smooth, poetic sentence.

Common Pitfalls:
Some candidates may be tempted to choose a non obvious pattern, thinking the exam must be trickier than it is. Others might not visualise the scene and instead try to guess mechanically. A reliable strategy in such questions is to imagine the scenario like a short film: what comes first, second, and third? Here, the progression from faint primrose light to golden bars to the full dawn across the desert makes the correct order intuitively clear.

Final Answer:
The most logical order of the labelled parts is XYZ, giving a coherent and vivid description of the dawn over the desert.