Rearrange the labelled parts X, Y and Z to form the most logical sentence:\n"Another major difference X. seven planets around the star Y. system is the tight packing of the Z. in comparison with the solar."

Introduction / Context:
This question presents a sentence about a planetary system compared with the solar system. The sentence is broken into three labelled fragments X, Y, and Z, and you must choose the order that results in a coherent and grammatically correct statement. It tests your ability to reconstruct scientific descriptions and recognise standard clause order, especially when comparing two systems.

Given Data / Assumptions:

• Fixed beginning: "Another major difference".
• X: "seven planets around the star"
• Y: "system is the tight packing of the"
• Z: "in comparison with the solar"
• The final sentence should compare one planetary system with the solar system.

Concept / Approach:
The sentence is clearly about comparing a particular exoplanetary system with our solar system. A natural structure in English is: "Another major difference in comparison with the solar system is the tight packing of the seven planets around the star." In this arrangement, the prepositional phrase "in comparison with the solar system" comes right after "difference", followed by "is the tight packing of the seven planets around the star". Therefore, we aim to place Z immediately after the opening phrase, then Y, and then X.

Step-by-Step Solution:
Step 1: Attach Z after the fixed beginning: "Another major difference in comparison with the solar". This sets up the comparison and is idiomatic in English.Step 2: Follow with Y: "system is the tight packing of the". This continues smoothly from "the solar system", giving "Another major difference in comparison with the solar system is the tight packing of the".Step 3: Close with X: "seven planets around the star". Now the full sentence reads: "Another major difference in comparison with the solar system is the tight packing of the seven planets around the star."Step 4: Map this order back to the options: we used Z first, then Y, then X, which corresponds to option (a) ZYX.

Verification / Alternative check:
Check grammatical correctness and science writing style. The resulting sentence follows the pattern: "Another major difference in comparison with the solar system is the tight packing of the seven planets around the star." This is typical scientific language when comparing planetary systems. Test a different order, such as YZX: "Another major difference system is the tight packing of the in comparison with the solar seven planets around the star." This is clearly ungrammatical and breaks the comparison structure. Similarly, ZXY or YXZ produce awkward or incomplete phrases, confirming that ZYX is the only viable order.

Why Other Options Are Wrong:

• Option (b) ZXY: Would lead to "... in comparison with the solar seven planets around the star system is the tight packing of the", which badly misorders the nouns and breaks the phrase "solar system".
• Option (c) YZX: Starts with "system is the tight packing of the", leaving "difference" without a proper completion and separating "solar system".
• Option (d) YXZ: Produces an equally jumbled sequence that does not clearly state what the difference is.

Common Pitfalls:
One common mistake is to keep the fragment "system is the tight packing of the" too close to the beginning, forgetting that "difference" needs a complete prepositional phrase to link it to "the solar system". Another pitfall is not preserving fixed combinations like "solar system". When rearranging fragments, always try to keep known collocations ("solar system", "planets around the star") together to maintain naturalness and clarity.

Final Answer:
The correct order is ZYX, giving the sentence: "Another major difference in comparison with the solar system is the tight packing of the seven planets around the star."