In the following question, a sentence is divided into four parts. Rearrange these parts to form a grammatically and contextually correct sentence.

(A) emissions in the region

(B) on lowering carbon

(C) the recent policy had

(D) a positive impact

The correct option is CDBA.

To form a grammatically correct and meaningful sentence, let us analyze the logical sequence of the given sentence parts:

1. (C) the recent policy had: This part introduces the main subject ("the recent policy") and the transitive verb ("had"). It serves as the opening part of the sentence.
2. (D) a positive impact: This part acts as the direct object following the verb "had", forming the clause "the recent policy had a positive impact".
3. (B) on lowering carbon: The noun "impact" is followed by the preposition "on". This phrase specifies the area affected by the impact ("on lowering carbon").
4. (A) emissions in the region: This part completes the object of the preposition "lowering carbon", resulting in "lowering carbon emissions in the region".

Putting all the parts together in the order C → D → B → A forms the coherent sentence:
"The recent policy had a positive impact on lowering carbon emissions in the region."

Therefore, the correct sequence is CDBA.