Rearrange the following sentence parts to form a meaningful and grammatically correct paragraph:

P. However, the climbers were caught off guard when an unexpected blizzard engulfed the ridge.

Q. Determined to reach the summit before nightfall, the team leader gave the signal to proceed.

R. The expedition’s goal of reaching the peak quickly transformed into a struggle to find shelter.

S. By taking the steeper route, they hoped to save valuable hours and complete the climb early.

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

To arrange the sentence parts into a meaningful and grammatically correct paragraph, we analyze the logical flow of events:

1. Sentence Q serves as the introductory statement ("Determined to reach the summit before nightfall, the team leader gave the signal to proceed."), establishing the initial decision to begin the climb.

2. Sentence S follows sentence Q ("By taking the steeper route, they hoped to save valuable hours and complete the climb early."), elaborating on how they planned to execute their attempt by choosing a specific route.

3. Sentence P introduces a major turning point or conflict ("However, the climbers were caught off guard when an unexpected blizzard engulfed the ridge."). The word "However" transitions from their optimistic plan to an unforeseen obstacle.

4. Sentence R provides the conclusion ("The expedition’s goal of reaching the peak quickly transformed into a struggle to find shelter."), describing the direct consequence of the blizzard introduced in sentence P.

Combining these sentences in order gives the coherent paragraph: Q, S, P, R.