The question below contains four scattered segments of a sentence. Indicate…

Concept: In a sentence-rearrangement item, the segment that opens the sentence must be a complete, self-sufficient clause. A segment that starts with a conjunction (so, but), a preposition (from, in), or a participial phrase (caused by...) cannot open the sentence — each of these needs something stated before it (a cause, a referent, or a noun to modify).

Application: test each segment as a possible opener.

• "so a new windstorm is coming" starts with the conjunction "so", which must follow a stated cause — it cannot open the sentence.

• "from the north now" starts with the preposition "from", leaving it without a verb or subject of its own — it cannot open the sentence.

• "caused by a windstorm in the distance" starts with the participial phrase "caused by", which needs a preceding noun to modify — it cannot open the sentence.

• "i can see a big cloud of dust" is a complete independent clause, so it must be the opening segment.

With "i can see a big cloud of dust" first, the dust is naturally explained by "caused by a windstorm in the distance", giving "a big cloud of dust caused by a windstorm in the distance". This stated cause then leads into the announced effect, "so a new windstorm is coming", which is completed by "from the north now". The assembled sentence reads: "I can see a big cloud of dust caused by a windstorm in the distance, so a new windstorm is coming from the north now." This gives the sequence b - d - a - c.

Cross-check: swapping the order of the last three segments breaks the flow — the cause-effect link between the dust and the windstorm, and between the windstorm and its direction, only holds together in this one order.