Step 1: Understanding the Question:
We are required to rearrange fragments P, Q, R, and S to build a meaningful, grammatically sound sentence.
Step 2: Key Concepts and Syntactic Analysis:
Let's analyze the grammatical connections:
1. Fragment Q ``the boy was trying'' acts as the subject and principal verb phrase.
2. The verb ``trying'' is followed by an infinitive verb phrase, which is provided in P: ``to understand the truth''. This links Q to P (QP).
3. ``The truth'' is naturally followed by the prepositional phrase in S: ``of what the'' (QPS).
4. Finally, the relative clause must be completed by the subject and verb in R: ``old man had said'' (QPSR).
The complete sentence reads: ``The boy was trying to understand the truth of what the old man had said.''
Step 3: Detailed Explanation:
• Option (A) - QPSR: This produces a grammatically perfect and highly cohesive sentence: ``The boy was trying to understand the truth of what the old man had said.''
• Option (B) - RQPS: This begins with ``old man had said...'' and results in an incomplete and fragmented structure.
• Option (C) - SQRP: This starts with ``of what the...'' which cannot open a standard declarative sentence.
• Option (D) - RPQS: This starts with the subordinate clause predicate, lacking grammatical order.
Step 4: Final Answer:
Thus, the correct and coherent sequence is QPSR, corresponding to Option (A).