Which of the following observations provides the strongest evidence that India's demographic transition remains incomplete?

Mortality rates have declined substantially, but birth rates have not declined to the same extent.

The correct answer is Option 2: Mortality rates have declined substantially, but birth rates have not declined to the same extent.

The passage identifies this specific imbalance as the reason India's demographic transition is not yet complete. The key issue is not population density or urbanisation but the differing pace of decline in birth and death rates.

Option 1: Population density remains high. Incorrect. High density alone does not determine the stage of demographic transition.

Option 2: Mortality rates have declined substantially, but birth rates have not declined to the same extent. Correct. This is the exact condition described.

Option 3: Agriculture continues to employ a large workforce. Incorrect. This may relate to development but does not directly indicate the stage of demographic transition.

Option 4: Urbanisation has increased over time. Incorrect. Urbanisation alone cannot establish whether the transition is complete.