Concept:The sentence has words placed in incorrect positions; swapping the right pairs restores correct grammar and meaning.
Explanation:The phrase "India's widespread dividend" should be "India's demographic dividend", so A (widespread) and D (demographic) must be swapped.
The phrase "focus on mitigate healthcare" should be "focus on preventive healthcare", and "to preventive the economic challenges" should be "to mitigate the economic challenges".
Thus, B (mitigate) and C (preventive) also need to be swapped.
After interchanging A‑D and B‑C, the sentence becomes: "Leveraging India's demographic dividend demands a focus on preventive healthcare to mitigate the economic and productivity challenges posed by widespread chronic diseases."
This version is grammatically correct and logically meaningful.
Answer:Option C (A‑D and B‑C) is the correct choice.