Rearrange the following sentences to form a meaningful and coherent paragraph:

P. Nevertheless, as its territories grew wider, a complex set of internal and external obstacles began to surface.

Q. The Venetian Republic was initially a flourishing maritime power, renowned for its strong naval fleet and financial prosperity.

R. Its ultimate downturn stemmed from shifting trade routes, administrative decay, fiscal deficits, and rising regional competition.

S. Such mounting strain severely compromised its commercial dominance, administrative stability, and defense networks.

The correct option is Q, P, S, R.

To form a coherent and meaningful paragraph, we can analyze the logical connections between the given sentences step-by-step:

1. Sentence Q: "The Venetian Republic was initially a flourishing maritime power..."
This sentence serves as the topic sentence because it introduces the main subject—The Venetian Republic—and establishes its background of initial prosperity and strong naval presence.
2. Sentence P: "Nevertheless, as its territories grew wider..."
The conjunction "Nevertheless" signals a contrast to the initial prosperity mentioned in Q, introducing the complex obstacles that arose with expansion. Therefore, P logically follows Q.
3. Sentence S: "Such mounting strain severely compromised..."
The phrase "Such mounting strain" directly refers back to the "internal and external obstacles" introduced in sentence P. Thus, S naturally follows P.
4. Sentence R: acquisition of long-term factors leading to the fall: "Its ultimate downturn stemmed from..."
This sentence summarizes the eventual collapse and provides a conclusive statement to the paragraph, making R the ideal concluding sentence.

Hence, the correct and logical arrangement is Q → P → S → R.