Concept:The question tests the ability to arrange jumbled sentence parts into a logical and grammatically correct sequence.
Explanation:The parts are: P: "a decade sooner than 2050", Q: "that the population will peak", R: "the second scenario suggested", S: "at 8.5 billion by 2040".
The subject "the second scenario suggested" (R) should begin the sentence to introduce what is being stated.
Next, the clause "that the population will peak" (Q) directly follows the verb "suggested".
Then, the phrase "at 8.5 billion by 2040" (S) specifies the target of the peak.
Finally, "a decade sooner than 2050" (P) adds the time comparison, completing the thought.
Thus, the correct order is R → Q → S → P, which corresponds to sequence RQSP.
The other options either start with a time phrase (P) or place details out of order, breaking clarity.
Answer:RQSP (Option B)